Formatting Primary Dimension Units

AutoCAD provides many ways to format dimension units. You can set the unit type, precision, fraction format, and decimal format. You can also add prefixes and suffixes. For example, you can add a diameter symbol as a prefix to a measurement or add a unit abbreviation, such as mm, as a suffix. You set the format for primary dimension units on the Primary Units tab in the New Dimension Style dialog box.
Under Linear Dimensions, you can set the format for linear, aligned, radius, diameter, ordinate, and nonangular baseline and continued dimensions.

  • Units Format: Sets the unit format—Scientific, Decimal, Engineering, Architectural, Fractional, Windows Desktop. (Windows Desktop uses the settings on the Windows Regional Settings control panel.) The following illustrations show examples of each format.


  • Precision: Sets the number of decimal places for units and shows the format in which values are displayed, depending on the unit type.
  • Fraction Format: Sets the format for fractional units Diagonal, Horizontal, or Not Stacked.
  • Decimal Separator: Sets the decimal separator—period (.), comma (,) or space ( )—unless you select Windows Desktop units, in which case AutoCAD uses the Decimal Symbol setting in the Regional Settings control panel.
  • Round Distances To: Rounds measurements to the specified value. For example, if you enter .05 as a round-off value, AutoCAD rounds 0.06 to 0.10, and 0.008 to 0.01. You can enter a rounding value up to five decimal places. The decimal precision of your rounding value should equal or be less than your Precision value.
  • Prefix: Specifies a prefix for the dimension measurement. If you enter a prefix, it replaces the radius and diameter prefixes that AutoCAD automatically adds to radius and diameter dimensions. You can use control codes and special characters to enter special prefix symbols.
  • Suffix: Specifies a suffix for the dimension measurement. You can use control codes and special characters to enter special suffix symbols.
  • Linear Scale Factor: Multiplies the measurement value of linear dimensions (linear, aligned, radius, diameter, ordinate, baseline, continued) by the value entered. For example, if you set the scale factor to 2.0, AutoCAD dimensions two-unit segments as 4.0 units. If you set it to .25, AutoCAD dimensions the two-inch segment as 0.5 units. See “Rounding Off Dimension Values.”
  • Scale Dimension to Layout: Applies the linear scale factor only to dimensions in layouts. See “Setting Dimension Scale.”

The following table shows control codes and special characters used to create common dimension prefixes and suffixes. See “Using Control Codes and Special Characters” under “TEXT” in the Command Reference.


You can set the format and precision for angular dimensions. Angular dimension options include Decimal Degrees, Deg/Min/Sec (degrees, minutes, seconds), Grads, and Radians.

You can suppress leading and trailing zeros for both linear and angular dimensions.


#1 David White on 01.13.10 at 5:37 am

I always wanted to dimension in both fractions and dimensions. I don’t want to flip in and out changing my setup in DIMSTYLE. I came up with the following routine. It does not change the dimension VALUE, it only changes the dimension FORMAT. The parameters shown for the rounding to 3 or 5 decimal places whether in decimals or fractions respectively.

I use it like this:

Commmand: ^C^Cspdim;dim;hor;\\\\

And all I have to enter before selecting the dimension points is either an F or a D depending on whether I want a fraction or decimal.

Save in notepad as SPDIM.LSP
Load with Command: (load “spdim”)

(defun c:spdim()
(initget “F D”)
(setq dse(getkword “Type: Dec/Frac”))
(if(= “F” dse)(setq ds 5))
(if(= “D” dse)(setq ds 2))
(setvar “dimlunit” ds)
(if(= 2 ds)(setvar “dimdec” 3))
(if(= 5 ds)(setvar “dimdec” 5))

#2 Lito on 01.13.10 at 11:07 am

@David White

Thanks for sharing!

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