Specify dimensions for Adobe Illustrator designs and add measurements with a Creative Cloud extension

Adobe Illustrator script and extension to automate specifying dimension measurements (and adding dimension lines) of single or multiple objects, and specifying the dimensions between two objects.

Check out the Specify extension docs for more detailed information.


Extension Install

Simply download the Specify extension from Adobe Exchange.

Extension Updates

To update to the latest version of the Specify extension:

  1. Open the Creative Cloud desktop app.
  2. Click to activate the Marketplace tab.
  3. Click Plugins, then Manage Plugins on the sidebar.
  4. Find the Specify extension in the list of plugins. If an update is available, simply click the Update button and then restart Illustrator.

Specify extension update instructions within Creative Cloud desktop app


To run the extension, first select one or more objects in your open Illustrator document. You must have at least one object selected via Illustrator's Selection Tool V or Direct Selection Tool A.

Extension Usage

After installing the Specify extension from Adobe Exchange, simply navigate to Window > Extensions > Specify to get started. Run the extension by simply clicking the "Specify Object(s)" button in the extension panel.

Options and Styles

When the extension initializes, you will be presented with a dialog that allows you to choose which dimension(s) of your object(s) you would like to specify. The dialog also allows for the customization of several options. Any changes to the settings defined in the Specify Dialog (including both the Options Panel and the Styles Panel) will persist until you close the Adobe Illustrator application, even if you run the extension in multiple documents.

After configuring your desired settings, make sure to select which dimension(s) to dimension, and then simply click the "Specify Object(s)" button at the bottom right of the dialog. Specify will quickly output all selected dimensions onto a new SPEC layer, and then lock the layer to prevent accidental edits.

SPEC Layer

You are free to unlock the SPEC layer and edit as needed. You may change the color of individual dimension labels, adjust the placement of dimension groups, or even remove dimensions you no longer need.

If you make a mistake, no problem! Simply select the desired objects and run the extension again.

Options Panel

The Options Panel allows the user to select the side(s) of the object(s) to dimension, to use decimals or fractions for non-whole-number measurements, whether to dimension the object itself or between objects, and the scale of the artwork.

Specify Illustrator Extension Options Panel


  • Default: None

The options panel allows you to first choose which dimension(s) of your Illustrator object you would like to specify. You may choose top, right, bottom, left, or any combination of sides.

Multiple Objects

  • Default: false

If exactly two objects are selected on your artboard, you will be given the option to dimension between the two objects, instead of their individual sides. When checked, this option will specify the selected dimension(s) between the two chosen objects.


  • Default: 1/1

You may define a custom scale for your artwork, which will apply a multiplier to the displayed units label.

For example, if you are designing an engineering drawing at 1/4 scale (or 1:4), you simply choose this ratio from the Scale dropdown menu, and then optionally enable the checkbox for Custom Units Text on the Styles Panel that corresponds to the unit labels you would like to output. In this example, choosing '1/4' will indicate the artwork is drawn at one-fourth scale, resulting in dimension values that are 4 times their drawn dimensions.

Decimals or Fractions


  • Default: 2

If you choose Decimals, you can specify how many decimal places to use for the measurement (0-5 decimal places). Trailing zeros will be automatically removed.


Maximum Denominator
  • Default: 64

If you choose to use Fractions you can specify the maximum denominator number to use. This setting will impact the rounding algorithm.

Include a dash
  • Default: checked

You may also choose whether to include a dash - between the whole number and the fraction. With this setting enabled, the measurement 1 3/4 is displayed as 1-3/4.

SPEC Layer

Choose whether to lock the SPEC layer after adding the dimensions.

Styles Panel

The Styles Panel allows the user to completely customize the label styles and the line styles for all dimensions.

Specify Illustrator Extension Styles Panel

Include Units in Label

  • Default: checked

When checked, inserts the units in the label alongside the dimension measurement.

The extension automatically dimensions objects based on the Document's default units. To dimension in different units (i.e. Inches, Centimeters, etc.), first, select show Rulers via View > Rulers > Show Rulers ( ⌘Cmd + R on Mac, Ctrl + R on PC ).

Next, right-click on the Ruler, and select your desired units. Otherwise, the extension will use the Document's selected units by default.

Custom Units Text

  • Default: false

When checked, allows the user to customize the text of the units label. For example, displaying the abbreviation for feet, "ft" instead of the ruler measurement unit.

Font Family

  • Default: Tahoma

Set the desired font family for the dimension label(s).

Font Size

  • Default: 8

Set the desired font size for the dimension label(s). If the value is less than one (e.g. 0.25) you must include a leading zero before the decimal point.


  • Default: rgb(36, 151, 227)

Click to select the color for the dimension label(s).


  • Default: 4

Set the size of the desired gap between the dimension label(s) and the object.

Stroke Width

  • Default: 1

Set the desired stroke width of the dimension line.

Head & Tail Length

  • Default: 6

Set the desired length of the line at both ends of the dimension line.


At the bottom left of the Specify dialog is a Reset button that restores all defaults in both the Options Panel and the Styles panel.


Do you have questions? Would you like to contribute? Something else? Feel free to open an issue on GitHub.

Not into looking at code? No worries. Reach out on Twitter @adamdehaven.


Specify Illustrator Extension Example

Specify Illustrator Extension Example 2