Change your drawing units in AutoCAD through the Drawing Setup dialog

To change measurement units in AutoCAD, open the Drawing Setup dialog by typing UNITS at the command line and pressing Enter. A dialog box appears with options for length units (inches, feet, millimeters, centimeters, or meters) and angle units. Select your preferred unit type, set the precision level, and click OK. The change applies when ready to new geometry you draw, though existing objects keep their original measurements — you are only changing how AutoCAD interprets and displays dimensions going forward.

If you work with a template file regularly, change the units once in that template and save it. Every new drawing based on that template will start with your preferred units already set, saving you the step on each project.

Key Takeaways

  • The UNITS command opens the dialog where you set length and angle units for your drawing.
  • Changing units affects how new objects are measured and displayed, but does not convert existing geometry.
  • You can set units in a template file so every new drawing starts with your preferred measurement system.
  • The precision setting controls how many decimal places or fractions appear in dimension text.
  • If you insert a drawing created in different units, AutoCAD will ask how to scale it relative to your current drawing.

Where to find the UNITS command

The UNITS command is the fastest way to access unit settings. Type UNITS at the command line (the text input area at the bottom of your screen) and press Enter. The Drawing Units dialog opens when ready.

If you prefer the menu, go to Format > Units. This path opens the same dialog. Either method works — use whichever feels natural to you.

Choosing length units for your project

The Drawing Units dialog shows a dropdown for Length with five standard options: Decimal Inches, Engineering (feet and decimal inches), Architectural (feet, inches, and fractions), Decimal Millimeters, and Decimal Centimeters. Select the one that matches your project type and industry standard.

Architectural drawings typically use feet and inches with fractions (1'-6 3/4"). Engineering drawings often use decimal inches or millimeters. Manufacturing and product design frequently use millimeters. Choose based on what your client expects to see and what your industry uses — the unit choice does not change how AutoCAD works internally, only how dimensions display.

The precision dropdown next to Length controls decimal places or fraction size. For architectural work, you might choose 1/16" (sixteenths of an inch). For engineering, you might choose 0.00 (two decimal places). Higher precision means more detail in dimension text; lower precision rounds to whole numbers or larger fractions.

Setting angle units and direction

Below Length, the Angle section lets you choose how angles display: Decimal Degrees, Degrees/Minutes/Seconds, Gradians, Radians, or Surveyor's Units. Most drawings use Decimal Degrees. The precision dropdown for angles works the same way as length precision — it controls how many decimal places appear.

The Direction section sets where 0 degrees points (usually East, the default) and whether angles increase counterclockwise (standard in mathematics) or clockwise (sometimes used in surveying). Leave these at default unless your project has a specific requirement.

What happens to existing drawings when you change units

Changing units does not rescale objects already in your drawing. If you draw a line 10 units long in inches, then switch to millimeters, that line is still 10 units long — but now AutoCAD interprets it as 10 millimeters instead of 10 inches, making it much smaller on screen. The geometry itself does not move or resize.

If you need to convert an existing drawing to different units, you must use the SCALE command to resize all objects proportionally. For example, to convert from inches to millimeters, scale everything by 25.4 (since 1 inch = 25.4 millimeters). This is a separate step from changing the unit display.

Using units in template files

A template file is a blank drawing with your preferred settings already configured. When you create a new drawing from a template, it inherits those settings — including units, layers, text styles, and dimension styles. This saves time if you work on similar projects repeatedly.

To create a template: set up a blank drawing with your preferred units and other settings, then go to File > Save As. In the Save As dialog, change the file type dropdown from .dwg to .dwt (drawing template). Give it a descriptive name like "Architectural_Feet_Inches.dwt" and save it in your templates folder. When you start a new drawing, AutoCAD will offer your template as an option.

Inserting drawings with different units

When you insert a drawing (or block) created in different units into your current drawing, AutoCAD detects the mismatch and asks how to handle it. You can choose to scale the inserted drawing to match your current units, or insert it at its original size. If you choose scaling, AutoCAD calculates the conversion automatically — for example, if you insert a drawing made in millimeters into one using inches, it scales by 1/25.4.

Pay attention to this dialog when inserting external files. Choosing the wrong option can make inserted geometry appear tiny or enormous relative to your other objects.

Frequently Asked Questions

Can I change units in the middle of a project?

Yes, but existing geometry will not rescale. If you change from inches to millimeters mid-project, objects drawn before the change stay their original size. New objects will be measured in millimeters. Use the SCALE command to resize existing geometry if needed, or start fresh with the correct units from the beginning.

What is the difference between Architectural and Engineering units?

Architectural units display feet and inches with fractions (like 10'-6 3/4"), common in building design. Engineering units show feet and decimal inches (like 10.5625'), used in civil and structural work. Both use feet as the base unit; they differ only in how inches are displayed.

Do I need to match my units to my client's units?

Yes, typically. If your client works in millimeters and you draw in inches, dimensions will confuse them. Set your units to match what your client expects to see in the final drawing. If you are unsure, ask before starting.

What happens if I insert a block from a different drawing?

AutoCAD detects the unit difference and asks whether to scale the block to match your current drawing's units. Choose yes to scale it proportionally, or no to insert it at its original size. If you choose wrong, you can undo and insert again.

Can I use custom units that are not in the dropdown?

The standard dropdown covers most needs, but you can type a custom unit name in the Length field if your industry requires it. However, AutoCAD still measures internally in the base unit you choose — a custom name is just a label for display purposes.