How to Set Lineweight

Quick answer: Lineweight determines how thick or thin an entity appears on screen and when printed. It can be set to ByLayer, ByBlock, Default, or a specific value, and is measured in millimetres or inches depending on LWUNITS.

What You Can’t Apply a Lineweight To

Planes, points, TrueType fonts, and raster images can’t have a lineweight assigned.

The Three Named Lineweight Options

• ByLayer: uses the current layer’s Lineweight property; changing that property affects every entity on the layer set to ByLayer at once.
• ByBlock: entities get the Default lineweight until they’re included in a block definition. Once that block is inserted into a drawing, they inherit the block’s own lineweight instead.
• Default: saved via LWDEFAULT; changing it affects every entity in the entire drawing set to Default, not just one layer’s worth.

System Variables

• CELWEIGHT: the lineweight for new entities.
• LWDEFAULT: the value of the Default lineweight.
• LWDISPLAY: controls whether lineweights display at all; click the LWT field in the Status Bar to toggle it.
• LWDISPLAYSCALE: the display scale for lineweights in the Model tab, accepting values between 0 and 1.

Printing Lineweights

This works differently depending on whether an entity uses an index colour or a true colour:

• Index colour: prints using its lineweight only if the Colour Table (CTB) or Plot Style (STB) is set to Use object lineweight. Otherwise, the printed lineweight comes from the entity’s colour or plot style instead.
• True colour: always prints using the object’s own lineweight, with no such override possible.

Frequently Asked Questions

Can I assign a lineweight to a raster image or TrueType font? No, lineweights can’t be applied to planes, points, TrueType fonts, or raster images.

Why isn’t my entity printing with the lineweight I set? If it uses an index colour, check that your Colour Table (CTB) or Plot Style (STB) is set to Use object lineweight. Without that, the lineweight comes from colour or plot style instead. True-colour entities don’t have this issue, they always print their own lineweight.

What’s the difference between the Default lineweight and ByLayer? ByLayer follows whatever lineweight the current layer specifies. Default is a single drawing-wide value, set via LWDEFAULT, that affects every entity across the whole drawing set to use it, regardless of layer.

How do I turn lineweight display on or off? Click the LWT field in the Status Bar, which toggles LWDISPLAY.