Metric vs. Imperial Linetype Scaling: Units, Conversion Factors and Best Practices

A linetype can look correct in one AutoCAD drawing and appear too small, too large, irregular, or almost continuous in another. This often happens when a linetype created for an imperial drawing is used in a metric drawing, or when the drawing convention changes between millimeters, meters, inches, and feet.

The geometry may be converted correctly while the dash lengths, spaces, text sizes, and symbol offsets stored in the linetype definition remain based on the original unit system.

Correcting the problem requires more than changing LTSCALE. You must consider:

  • the unit represented by one drawing unit;
  • the values stored in the .LIN file;
  • LTSCALE;
  • CELTSCALE;
  • the object’s Linetype scale property;
  • MSLTSCALE and the active annotation scale;
  • PSLTSCALE in layout viewports;
  • PLINEGEN for polylines;
  • INSUNITS for blocks and Xrefs;
  • the text styles, fonts, and shape files used by complex linetypes.

This guide explains how metric and imperial linetype scaling works, which conversion factors to use, and how to maintain consistent patterns across drawings, blocks, Xrefs, model space, and layouts.

Understanding Metric and Imperial Drawing Units

How AutoCAD Interprets Drawing Units

AutoCAD geometry does not have a fixed physical unit by itself. A line measuring 100 drawing units does not automatically represent 100 millimeters, 100 inches, or 100 meters.

The meaning of one drawing unit depends on the convention selected for the project.

For example:

  • in a metric architectural drawing, 1 drawing unit may represent 1 millimeter;
  • in a civil engineering drawing, 1 drawing unit may represent 1 meter;
  • in an imperial architectural drawing, 1 drawing unit normally represents 1 inch;
  • in an imperial civil drawing, 1 drawing unit may represent 1 foot.

The UNITS command controls how distances, coordinates, angles, and precision are displayed. It does not automatically resize existing geometry or convert loaded linetype definitions.

The INSUNITS variable identifies the intended insertion unit of the drawing. AutoCAD uses this information when calculating scale factors for inserted blocks, attached Xrefs, images, and other referenced content.

Common Metric Drawing Conventions

Drawing convention Meaning of one drawing unit Common applications
Millimeters 1 unit = 1 mm Architecture, mechanical drafting, fabrication
Centimeters 1 unit = 1 cm Interior design and some legacy drawings
Meters 1 unit = 1 m Civil engineering, surveying, site plans

A wall measuring five meters may therefore be drawn as:

  • 5000 units in a millimeter-based drawing;
  • 500 units in a centimeter-based drawing;
  • 5 units in a meter-based drawing.

Common Imperial Drawing Conventions

Drawing convention Meaning of one drawing unit Common applications
Decimal inches 1 unit = 1 inch Mechanical drafting and manufacturing
Architectural units 1 unit = 1 inch Architecture and construction
Decimal feet 1 unit = 1 foot Civil engineering and surveying

Architectural dimensions may be displayed in feet and inches, but the underlying drawing unit normally remains the inch.

For example, a ten-foot wall is generally 120 drawing units long:

10 feet × 12 inches = 120 inches

Why Unit Conventions Affect Linetype Display

A linetype pattern is built from numerical values representing visible dashes, empty spaces, dots, text, and symbols.

Consider this simple definition:

*CUSTOM_DASH,Custom dashed line
A,0.50,-0.25

The visible dash is 0.50 drawing units long, and the following space is 0.25 drawing units long before other scale factors are applied.

If one drawing unit represents one inch, the dash is half an inch long.

If one drawing unit represents one millimeter, the same numerical dash is only half a millimeter long.

The .LIN definition has not changed, but its physical meaning changes because the drawing uses a different unit convention.

How Linetype Patterns Store Their Measurements

Anatomy of a Simple LIN Pattern

A simple linetype definition normally contains two lines:

*CUSTOM_DASH,Custom dashed line
A,0.50,-0.25

The first line is the header:

*CUSTOM_DASH,Custom dashed line

It contains:

  • an asterisk;
  • the linetype name;
  • a comma;
  • an optional description.

The second line defines the pattern:

A,0.50,-0.25

The letter A indicates an aligned pattern. The numerical values define the visible and invisible parts of the sequence.

Positive, Negative, and Zero Values

AutoCAD interprets the values as follows:

  • a positive value creates a visible dash;
  • a negative value creates an empty space;
  • a value of zero creates a dot.

For example:

*DASH_DOT_EXAMPLE,Dash dot example
A,0.50,-0.20,0,-0.20
Value Result
0.50 Visible dash
-0.20 Empty space
0 Dot
-0.20 Empty space

The complete sequence repeats along the object.

LIN Files Do Not Store an Automatic Unit System

A .LIN file does not contain a universal instruction declaring that its values are inches, millimeters, feet, or meters.

The pattern only contains numbers.

A linetype is considered metric or imperial because its numerical values were designed to produce an appropriate appearance in a specific drawing convention.

This means that a custom .LIN file must be documented clearly. Without documentation, another user may load an inch-based definition into a millimeter drawing and assume that the pattern will be converted automatically.

It will not.

ACAD.LIN, ACADISO.LIN, MEASUREMENT, and MEASUREINIT

What ACAD.LIN Is Used For

acad.lin is normally associated with imperial drawings.

Its standard patterns are sized for workflows in which one drawing unit commonly represents one inch.

Typical linetypes include:

  • DASHED;
  • HIDDEN;
  • CENTER;
  • PHANTOM;
  • BORDER.

What ACADISO.LIN Is Used For

acadiso.lin is normally associated with metric drawings.

It includes many of the same names as acad.lin, but the pattern values are generally larger so that the linetypes produce a comparable physical appearance in millimeter-based drawings.

Identical Names Can Contain Different Patterns

Both files may contain linetypes named CENTER, HIDDEN, or DASHED, but identical names do not guarantee identical numerical definitions.

An imperial and a metric version may use the same pattern proportions while their values differ by approximately 25.4.

This becomes important when objects are copied between drawings. If the destination drawing already contains a linetype with the same name, AutoCAD may continue using the definition already stored in the destination file.

The MEASUREMENT Variable

MEASUREMENT is stored in the current drawing.

Its common values are:

MEASUREMENT = 0

for imperial resource conventions, and:

MEASUREMENT = 1

for metric resource conventions.

This variable influences which hatch and linetype resource conventions AutoCAD uses when loading standard content.

Changing MEASUREMENT does not automatically replace linetypes that are already loaded in the drawing.

The MEASUREINIT Variable

MEASUREINIT controls the initial measurement convention used for new drawings created without a template.

It can also affect the default measurement environment used when opening or importing neutral files that do not contain a complete AutoCAD drawing setup, such as some DXF or exchanged files.

Common values are:

MEASUREINIT = 0

for imperial defaults, and:

MEASUREINIT = 1

for metric defaults.

The distinction is important:

  • MEASUREMENT applies to the current drawing;
  • MEASUREINIT defines the default convention for certain new or neutral drawings.

A properly configured company template remains the most reliable method because it can store the correct units, linetypes, layers, text styles, annotation scales, and plotting settings together.

Reloading Linetype Definitions After Changing Units

Changing MEASUREMENT does not reload existing linetypes from another .LIN file.

To replace definitions, use the command-line version of the Linetype command:

-LINETYPE

Depending on the AutoCAD language, the command name may appear differently, but the underscore-prefixed international form can be used in scripts:

_-LINETYPE

A controlled reload process normally involves:

  1. identifying the correct metric or imperial .LIN file;
  2. reloading the required linetype names;
  3. confirming replacement when AutoCAD detects an existing definition;
  4. running REGENALL;
  5. checking blocks, Xrefs, and layouts.

For multiple drawings or many linetypes, a script, AutoLISP routine, or standards-management tool can automate the reload and overwrite process.

This is safer than changing definitions manually in dozens of DWG files.

Essential Conversion Factors

The most important factor for imperial and metric linetype conversion is the relationship between inches and millimeters:

1 inch = 25.4 millimeters

The main conversion factors are:

Source convention Target convention Operation
Inches Millimeters Multiply by 25.4
Millimeters Inches Divide by 25.4
Feet Inches Multiply by 12
Inches Feet Divide by 12
Feet Millimeters Multiply by 304.8
Millimeters Feet Divide by 304.8
Feet Meters Multiply by 0.3048
Meters Feet Multiply by 3.280839895
Millimeters Meters Divide by 1000
Meters Millimeters Multiply by 1000

These factors apply to the numerical dimensions stored in a linetype definition.

They should not be applied automatically without first identifying the drawing unit and the unit for which the .LIN file was created.

How to Convert a Linetype Definition Between Units

Converting an Imperial Linetype to Millimeters

Consider this inch-based linetype:

*CUSTOM_DASH_IN,Custom imperial dashed line
A,0.50,-0.25

Multiply every length by 25.4:

0.50 × 25.4 = 12.70
0.25 × 25.4 = 6.35

The metric definition becomes:

*CUSTOM_DASH_MM,Custom metric dashed line
A,12.70,-6.35

Both versions now represent the same physical dimensions:

  • 0.50 in = 12.70 mm;
  • 0.25 in = 6.35 mm.

Converting a Millimeter Linetype to Inches

Consider this metric definition:

*CUSTOM_DASH_MM,Custom metric dashed line
A,20,-10

Divide each value by 25.4:

20 ÷ 25.4 = 0.7874016
10 ÷ 25.4 = 0.3937008

The imperial version becomes:

*CUSTOM_DASH_IN,Custom imperial dashed line
A,0.7874,-0.3937

The required number of decimal places depends on the pattern and the drafting standard. Avoid excessive rounding when short segments or detailed symbols are involved.

Converting a Millimeter Pattern to Meters

Suppose a pattern was designed for a millimeter-based drawing:

*UTILITY_MM,Utility line for millimeter drawings
A,100,-50

For a meter-based drawing, divide the values by 1000:

100 mm ÷ 1000 = 0.1 m
50 mm ÷ 1000 = 0.05 m

The meter-based definition becomes:

*UTILITY_M,Utility line for meter drawings
A,0.1,-0.05

Convert Every Relevant Value

For a simple linetype, review:

  • dash lengths;
  • gap lengths;
  • dot spacing.

For a complex linetype, also review:

  • text scale;
  • shape scale;
  • X offsets;
  • Y offsets;
  • distances before and after text;
  • distances before and after symbols.

Use the same conversion factor throughout the complete definition.

Converting the dashes without converting the spaces or offsets changes the pattern proportions and can cause text or symbols to overlap.

LTSCALE, CELTSCALE, and Object Linetype Scale

LTSCALE: Global Linetype Scale

LTSCALE controls the global scale applied to non-continuous linetypes in the drawing.

A simplified formula is:

Displayed pattern =
LIN pattern value × LTSCALE × object linetype scale

For example, consider:

A,10,-5

With:

LTSCALE = 1
Object linetype scale = 1

the nominal dash length is ten drawing units.

With:

LTSCALE = 2
Object linetype scale = 1

the displayed dash becomes twenty drawing units long.

A larger LTSCALE produces longer dashes and spaces. A smaller value produces shorter dashes and spaces.

CELTSCALE: Initial Scale for New Objects

CELTSCALE defines the linetype scale assigned to newly created objects.

For example:

CELTSCALE = 2

causes new objects to receive an individual linetype scale of 2.

Changing CELTSCALE does not update objects that already exist.

For a standardized drawing environment, CELTSCALE is commonly kept at:

CELTSCALE = 1

It is important not to count CELTSCALE twice.

Once an object is created, its stored Linetype scale property normally reflects the scale assigned at creation. The ongoing display calculation uses the object’s stored scale rather than repeatedly multiplying a separate CELTSCALE value.

For newly created objects that retain the current setting, the practical relationship can be described as:

Initial object scale = CELTSCALE

followed by:

Displayed pattern =
LIN pattern value × LTSCALE × stored object linetype scale

Object Linetype Scale

Each applicable object can have its own Linetype scale property.

For example:

Object linetype scale = 0.5

displays the pattern at half the size produced by the global setting.

A value of:

Object linetype scale = 4

displays it four times larger.

Object-level overrides are useful for justified exceptions, but hundreds of different values make a drawing difficult to audit and maintain.

Why LTSCALE Is Not a Permanent Unit Conversion Method

An inch-based linetype may be made visually acceptable in a millimeter drawing by applying a scale factor near 25.4.

However, changing LTSCALE affects all scalable linetypes in the drawing, including patterns that may already be correctly defined.

It may also complicate:

  • blocks;
  • Xrefs;
  • object-level overrides;
  • layouts;
  • company templates;
  • drawing exchanges.

For a permanent standard, use a .LIN definition designed for the actual drawing unit and keep the main scale settings consistent.

MSLTSCALE and the Active Annotation Scale

How MSLTSCALE Works

MSLTSCALE controls whether the active annotation scale affects linetype display in model space.

When:

MSLTSCALE = 1

AutoCAD uses the current annotation scale, represented by CANNOSCALE, when displaying linetypes in model space.

Examples of active annotation scales include:

1:20
1:50
1:100
1/4" = 1'-0"
1/8" = 1'-0"

Changing CANNOSCALE can therefore change the visual size of linetype patterns in model space even when LTSCALE and the object scale remain unchanged.

Effective Scale in Model Space

For an existing object, the practical model-space relationship when MSLTSCALE = 1 is:

Effective pattern factor =
LTSCALE × object linetype scale × annotation-scale factor

For a newly created object whose linetype scale is still equal to CELTSCALE, the relationship may be expressed as:

Effective pattern factor =
LTSCALE × CELTSCALE × annotation-scale factor

If an additional object-level override is later applied, use the stored object value instead of multiplying CELTSCALE again.

This distinction is important because CELTSCALE initializes the object property; it is not a permanent independent multiplier added on top of that same stored property.

When MSLTSCALE Is Set to 0

When:

MSLTSCALE = 0

the active annotation scale does not adjust the model-space linetype display.

The pattern then depends primarily on:

  • the .LIN values;
  • LTSCALE;
  • the object’s Linetype scale property.

This may be preferred in workflows where linetypes are controlled entirely through drawing units and explicit scale values.

PSLTSCALE and Layout Viewports

Consistent Paper-Space Appearance

PSLTSCALE controls how linetypes are displayed through layout viewports.

When:

PSLTSCALE = 1

AutoCAD adjusts the display so that linetypes have a more consistent paper-space appearance across viewports using different scales.

For example, a dashed line shown in a 1:20 viewport and the same type of line shown in a 1:100 viewport can have similar dash lengths on the printed sheet.

Model-Based Appearance

When:

PSLTSCALE = 0

the linetype pattern follows model-space scaling more directly.

Its apparent size on paper therefore changes according to the viewport scale.

This setting may be appropriate when the linetype dimensions are intended to represent actual model distances rather than a consistent printed symbol pattern.

Common Layout-Based Starting Settings

A common starting configuration is:

LTSCALE = 1
CELTSCALE = 1
MSLTSCALE = 1
PSLTSCALE = 1

This setup works best when:

  • the .LIN definitions match the drawing units;
  • annotation scales are correct;
  • viewport scales are standardized;
  • object linetype scales remain at 1.

It is not a universal rule. Civil, mapping, mechanical, and legacy projects may require different values.

After changing MSLTSCALE, PSLTSCALE, CANNOSCALE, or LTSCALE, run:

REGENALL

PLINEGEN and Linetype Generation on Polylines

Why a Polyline Can Appear Continuous

A common linetype problem is caused by PLINEGEN, not by the unit conversion or LTSCALE.

A polyline may contain many short segments. When the linetype pattern restarts at every vertex, each segment may be too short to display a complete dash-and-gap sequence.

The result can look continuous even though the correct linetype is assigned.

PLINEGEN = 0

When:

PLINEGEN = 0

the linetype pattern restarts at each polyline vertex.

This behavior may produce:

  • incomplete dashes;
  • irregular spacing;
  • continuous-looking short segments;
  • a different appearance around corners.

This setting is common in older drawings and legacy templates.

PLINEGEN = 1

When:

PLINEGEN = 1

AutoCAD generates the linetype continuously across the full polyline length.

The pattern passes through vertices instead of restarting independently on each segment.

This generally produces a more regular appearance on:

  • road centerlines;
  • utility lines;
  • property boundaries;
  • contours;
  • piping routes;
  • polylines with many short segments.

Object-Level Linetype Generation Property

Existing polylines may also have a Linetype generation property in the Properties palette.

Changing the global PLINEGEN variable mainly controls the behavior of subsequently created polylines. Existing objects may need to be updated individually or in a selection set.

When a dashed polyline appears continuous, verify:

  1. the assigned linetype;
  2. LTSCALE;
  3. the object’s linetype scale;
  4. PLINEGEN;
  5. the object’s Linetype generation property;
  6. the length of its individual segments;
  7. whether the drawing has been regenerated.

Recommended Scale Strategy by Drawing Unit

There is no universal LTSCALE value for all drawings.

The correct setup depends on:

  • the unit used by the .LIN definition;
  • the drawing unit;
  • the intended printed dash size;
  • the annotation scale;
  • the layout workflow;
  • the company standard.

If a linetype was originally created for millimeter-based drawings, possible mathematical compensation factors include:

Drawing convention Relationship to millimeters Possible compensation
Millimeters 1 unit = 1 mm 1
Centimeters 1 unit = 10 mm 0.1
Meters 1 unit = 1000 mm 0.001
Inches 1 unit = 25.4 mm 0.0393701
Feet 1 unit = 304.8 mm 0.00328084

These are conversion factors, not mandatory AutoCAD settings.

A dedicated .LIN file for the target drawing unit is normally easier to maintain than a template that depends on an unusual global scale value.

Linetypes Inside Blocks and Xrefs

What INSUNITS Actually Scales

When an inch-based block is inserted into a millimeter-based drawing, AutoCAD may apply an insertion factor of:

25.4

This resizes the block geometry.

However, INSUNITS does not convert the internal .LIN definitions used by the entities inside the block.

It also does not rewrite:

  • the host drawing’s LTSCALE;
  • the component objects’ stored linetype scales;
  • custom dash and gap values;
  • text scale values in complex linetypes;
  • shape offsets.

The geometry may therefore be the correct size while the linetype pattern still appears wrong.

Blocks with ByLayer, ByBlock, and Direct Assignments

The final appearance also depends on how the objects inside the block were configured.

Objects may use:

  • ByLayer;
  • ByBlock;
  • a directly assigned linetype.

A directly assigned custom linetype may behave differently from an object inheriting the host layer’s linetype.

When troubleshooting a block, inspect both:

  • the inserted block reference;
  • the original entities inside the block definition.

Xrefs Created in Different Units

When an Xref uses different units from the host drawing, verify:

  1. the host drawing’s INSUNITS;
  2. the Xref drawing’s INSUNITS;
  3. the calculated insertion factor;
  4. the LTSCALE values;
  5. object linetype scales;
  6. annotation and viewport settings;
  7. duplicate linetype names;
  8. whether the correct .LIN definitions are loaded.

A correct Xref insertion scale does not guarantee a correct linetype pattern.

Avoid Duplicate Names for Different Definitions

Do not use the same custom name for metric and imperial patterns.

Prefer names such as:

CUSTOM_CENTER_MM
CUSTOM_CENTER_IN
CUSTOM_CENTER_M
CUSTOM_CENTER_FT

Discipline-specific names are also useful:

GAS_LINE_MM
PROPERTY_LINE_FT
FENCE_METRIC
SURVEY_BOUNDARY_IMPERIAL

A company working in both unit systems should maintain separate libraries:

Company_Linetypes_Metric.lin
Company_Linetypes_Imperial.lin
Company_Linetypes_Meters.lin

Complex Linetypes with Text and Shapes

Why Complex Linetypes Require Additional Checks

A complex linetype may include:

  • text;
  • symbols;
  • SHX shapes;
  • rotation settings;
  • X and Y offsets;
  • embedded scale values.

Consider this metric example:

*GAS_LINE_MM,Gas line with text
A,12.7,-5.08,["GAS",STANDARD,S=2.54,R=0.0,X=-1.27,Y=-1.27],-5.08

The definition contains several dimensional values:

  • 12.7 for the visible dash;
  • 5.08 for the spaces;
  • 2.54 for the text scale;
  • -1.27 for the X and Y offsets.

All relevant dimensions must be reviewed during conversion.

Converting the Complex Pattern to Inches

Divide the dimensional values by 25.4:

*GAS_LINE_IN,Gas line with text
A,0.5,-0.2,["GAS",STANDARD,S=0.1,R=0.0,X=-0.05,Y=-0.05],-0.2

The rotation value remains unchanged because it is angular rather than linear.

Text Style Height

A text style with a fixed height can interfere with the size specified in the linetype definition.

For many complex linetypes, a text style height of:

0

is preferred because the S= value in the .LIN file can then control the text scale.

The correct setup still depends on the drafting standard and the CAD application being used.

Font Width Can Change the Pattern

The selected font affects more than the appearance of the letters.

Different fonts have different character widths.

For example:

  • txt.shx is relatively narrow;
  • simplex.shx has different proportions;
  • Arial.ttf may be noticeably wider;
  • another TrueType font may use different spacing and kerning.

If the offsets and surrounding spaces in the .LIN file were calculated for a narrow SHX font, changing the text style to a wider TrueType font may cause the word to overlap the adjacent dashes.

For example, the text "GAS" may fit correctly with txt.shx but collide with the following dash when the style uses Arial.

When changing fonts, verify:

  • the character width;
  • the text style width factor;
  • the S= scale;
  • the X= offset;
  • the spaces before and after the text;
  • the plotted result at the required scale.

The font is therefore a functional part of a complex linetype, not only a visual preference.

Shape-Based Linetypes

A shape-based linetype may depend on an external .SHX file.

When transferring the definition:

  • copy the required .SHX file;
  • place it in a valid support path;
  • preserve the shape name;
  • verify the shape scale;
  • verify X and Y offsets;
  • test the result in model space and layouts.

Unit conversion cannot correct a missing or incompatible shape file.

Common Scaling Problems and Their Causes

Symptom Likely cause What to check
Pattern is about 25.4 times too small Inch definition used in millimeters Load or create the metric definition
Pattern is about 25.4 times too large Metric definition used in inches Load or create the imperial definition
Pattern differs by a factor of 12 Inches and feet were confused Check the drawing-unit convention
Pattern differs by a factor of 1000 Millimeters and meters were confused Check the source .LIN unit
Pattern looks correct in model space but wrong in layouts Viewport scaling issue Check PSLTSCALE and regenerate
Pattern changes when CANNOSCALE changes MSLTSCALE is active Check MSLTSCALE and annotation scale
Polyline appears continuous Pattern restarts at vertices Check PLINEGEN and Linetype generation
Pattern changes after copying objects Duplicate linetype name Reload or rename the definition
Block geometry is correct but pattern is wrong INSUNITS only scaled the geometry Check internal LIN and object scales
Text overlaps adjacent dashes Font is wider than expected Check font, offsets, and text scale
Linetype still looks continuous Object is too short or scale is too small Test a longer object and run REGENALL

Step-by-Step Troubleshooting Workflow

Step 1: Identify the Real Drawing Unit

Do not rely only on the UNITS dialog box.

Measure a known object.

Examples:

  • a 900 mm door should measure approximately 900 in a millimeter drawing;
  • the same door should measure 0.9 in a meter drawing;
  • a three-foot door should measure 36 in an inch-based drawing;
  • it should measure 3 in a foot-based drawing.

Also check:

INSUNITS
MEASUREMENT

Step 2: Identify the Linetype Source

Determine whether the linetype came from:

  • acad.lin;
  • acadiso.lin;
  • a custom .LIN file;
  • a company template;
  • an inserted block;
  • an Xref;
  • another DWG file.

Step 3: Inspect the Definition

Open the .LIN file in a plain-text editor.

Review:

  • dash lengths;
  • spaces;
  • text scale;
  • shape scale;
  • X and Y offsets;
  • required text styles;
  • required fonts;
  • required .SHX files.

Step 4: Reset the Main Scale Settings

For a controlled test, use:

LTSCALE = 1
CELTSCALE = 1

Select a test object and set:

Linetype scale = 1

Then run:

REGENALL

Step 5: Check Annotation and Viewport Scaling

Verify:

MSLTSCALE
CANNOSCALE
PSLTSCALE

Determine whether the pattern changes because of model-space annotation scaling or layout viewport scaling.

Step 6: Check Polylines

For polylines, verify:

PLINEGEN

Also inspect the object’s Linetype generation property.

If the pattern restarts at each vertex, enable continuous generation and regenerate the drawing.

Step 7: Check Blocks and Xrefs

Verify:

  • source and target INSUNITS;
  • insertion scale;
  • internal object linetype scales;
  • duplicate linetype names;
  • whether the correct definition is stored in the host drawing.

Remember that INSUNITS scales geometry but does not convert .LIN values.

Step 8: Reload the Correct Definition

Use:

-LINETYPE

to reload the correct linetype from the required .LIN file.

For many drawings, use a script or AutoLISP routine to reload and overwrite definitions consistently.

Step 9: Test the Printed Result

Check:

  • long and short objects;
  • lines and polylines;
  • blocks;
  • Xrefs;
  • several annotation scales;
  • several viewport scales;
  • print preview;
  • exported PDF output.

A linetype should be approved according to its printed appearance, not only its appearance at one zoom level in model space.

Best Practices for Metric and Imperial Linetype Management

Use the Correct Library from the Beginning

Use:

  • acad.lin for standard imperial conventions;
  • acadiso.lin for standard metric conventions;
  • dedicated custom files for feet, meters, and company standards.

Keep Scale Settings Standardized

Maintain documented values for:

  • LTSCALE;
  • CELTSCALE;
  • MSLTSCALE;
  • PSLTSCALE;
  • PLINEGEN.

Avoid solving every drawing with a different unexplained global value.

Keep Object Linetype Scale at 1 When Possible

Object-level overrides should remain exceptions.

A drawing containing many unrelated object scales is difficult to:

  • audit;
  • update;
  • transfer;
  • reference;
  • print consistently.

Create Separate Templates

Maintain dedicated templates such as:

Company_Architectural_Imperial.dwt
Company_Architectural_Metric.dwt
Company_Civil_Feet.dwt
Company_Civil_Meters.dwt

Each template should contain:

  • the correct units;
  • the correct INSUNITS;
  • approved linetypes;
  • standard layers;
  • text styles and fonts;
  • annotation scales;
  • layout settings;
  • documented linetype variables.

Document Custom Linetype Dependencies

For each custom linetype, record:

  • the source unit;
  • the target unit;
  • the conversion factor;
  • the required text style;
  • the required font;
  • the required .SHX file;
  • the expected plotted size;
  • the recommended scale settings;
  • the software versions tested.

Test at Real Plot Scales

Test metric linetypes at scales such as:

  • 1:10;
  • 1:20;
  • 1:50;
  • 1:100;
  • 1:200;
  • 1:500.

Test imperial linetypes at scales such as:

  • 3″ = 1′-0″;
  • 1 1/2″ = 1′-0″;
  • 1/2″ = 1′-0″;
  • 1/4″ = 1′-0″;
  • 1/8″ = 1′-0″;
  • 1″ = 20′;
  • 1″ = 50′.

The pattern should remain readable without overpowering the drawing.

Practical Conversion Examples

Imperial Dashed Line Used in Millimeters

Original definition:

*ROAD_EDGE_IN,Road edge imperial
A,1.0,-0.5

Converted definition:

*ROAD_EDGE_MM,Road edge metric
A,25.4,-12.7

Use the metric version in a millimeter-based drawing and begin testing with:

LTSCALE = 1
Object linetype scale = 1

Millimeter Linetype Used in Meters

Original definition:

*FENCE_MM,Fence line in millimeters
A,200,-100,0,-100

Converted definition:

*FENCE_M,Fence line in meters
A,0.2,-0.1,0,-0.1

The zero remains unchanged because a dot has no length to convert.

Polyline with Short Segments

A road centerline uses a dashed linetype but appears almost continuous.

The .LIN definition and LTSCALE are correct.

The polyline contains many short segments, and:

PLINEGEN = 0

The pattern restarts at every vertex.

Set continuous linetype generation for the polyline, use:

PLINEGEN = 1

for new polylines, and run:

REGENALL

Complex Linetype with the Wrong Font

A gas line was designed with txt.shx, but the STANDARD text style now uses Arial.

The word "GAS" is wider and overlaps the following dash.

Possible corrections include:

  • restoring the intended SHX font;
  • creating a dedicated text style for the linetype;
  • adjusting the text scale;
  • increasing the surrounding spaces;
  • changing the X offset;
  • testing the result at the final plot scale.

Frequently Asked Questions

Should I use ACAD.LIN or ACADISO.LIN?

Use acad.lin for standard imperial drawings and acadiso.lin for standard metric drawings.

For custom company standards, use a dedicated .LIN file designed for the actual drawing unit.

Does changing UNITS convert linetypes?

No. UNITS changes the display and interpretation settings of the drawing. It does not rewrite loaded .LIN definitions or automatically resize existing geometry.

What is the difference between MEASUREMENT and MEASUREINIT?

MEASUREMENT applies to the current drawing.

MEASUREINIT defines the initial imperial or metric convention used for certain new drawings created without a template and some neutral-file workflows.

Can LTSCALE convert an imperial linetype to metric?

LTSCALE can compensate visually, but it does not rewrite the definition.

For a permanent standard, load or create a .LIN file designed for the target unit system.

Does INSUNITS convert the linetypes inside a block?

No. INSUNITS scales the block geometry during insertion.

It does not convert the .LIN pattern values, internal text scales, shape offsets, or stored object linetype scale properties.

Why does changing CANNOSCALE change my linetypes?

When MSLTSCALE = 1, the active annotation scale affects the visual linetype scale in model space.

Changing CANNOSCALE therefore changes the displayed pattern size.

Why do dashed polylines appear continuous?

The pattern may be restarting at every vertex.

Check PLINEGEN and the object’s Linetype generation property, especially when the polyline contains short segments.

Why do complex linetypes change when I replace the font?

Fonts use different character widths.

A pattern designed for a narrow SHX font may overlap when the text style is changed to a wider TrueType font.

Review the font, text scale, offsets, and surrounding spaces.

How can I reload many linetypes after changing standards?

Use the command-line -LINETYPE command for individual drawings.

For many files or many definitions, use a script, AutoLISP routine, or CAD standards tool to reload and overwrite the required names from the approved .LIN file.

Final Recommendations

Reliable metric and imperial linetype scaling begins with identifying the real drawing unit and the unit for which the .LIN definition was created.

Follow these rules:

  • use the correct metric or imperial linetype library;
  • keep custom metric and imperial definitions in separate files;
  • use clear suffixes such as _MM, _M, _IN, and _FT;
  • keep LTSCALE, CELTSCALE, and object scales standardized;
  • understand the interaction between MSLTSCALE and CANNOSCALE;
  • check PSLTSCALE in layouts;
  • check PLINEGEN on polylines;
  • remember that INSUNITS scales geometry but does not convert linetype definitions;
  • verify fonts and text styles in complex patterns;
  • reload definitions when changing from imperial to metric resources;
  • run REGENALL after changing linetype settings;
  • test every pattern at the actual plotting scale.

A consistent unit strategy prevents most linetype scaling problems. It also makes drawings easier to exchange, reference, print, audit, and maintain across teams working with different measurement systems.

Similar Posts