The Standard for AutoCAD Line Weights

By Alex Cosper

AutoCAD is drafting software that can be used to make machinery, quilts, clothes, architecture and many types of invention prototypes. AutoCAD has access to many industry standards, but it also allows project leaders to set their own flexible standards, which can be enforced with tool palettes. Standards for line weights, which are measured in millimeters, are not universal and depend on drawing complexity.

Line Weight

Line weight, or thickness of a line used in a drawing, is helpful for delineating specific details in complex hard copy drawings. Usually thick lines represent the most visible lines of your project while thin and medium lines provide detail. Architects use two separate line weight standards for CAD and hard copy drawing.

Color Coding

In CAD systems, color selection can control line weights as well as other line attributes. On a computer screen, line thickness can be better represented with colors. The ISO/DIN line weight color coding system has been widely used by architects. This system uses magenta (.18mm), white (.25mm), yellow (.35mm), red/brown (.50mm), cyan/blue (.70mm) and green (1.00mm) to represent line weights.

Thick Lines

Continuous thick (.35-50mm) lines are for definitive outlines and edges or preexisting features, while chain thick (also .35-.50mm) lines are used to depict pipelines and services. A continuous medium (.25-.35mm) line can simply be used for emphasis. A dashed thick (.35-.50mm) line depicts a hidden outline or edge. Line weights .4mm to .5mm are used to construct object lines for machine parts. Borders are made with .7mm line weight.

Thin Lines

Thin lines usually fall into the .18 to .25mm range of line weights. Continuous thin lines are used for proposed or imagined outlines. Chain thin lines and dashed thin lines are used to illustrate motion, center points, paths and repetition. Doors, cabinets and stairs are drawn with a line weight of .3mm, while lower line weights are used for hidden lines, elevations and dimensions.