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Adobe InDesign: Need Fractions?

by Barb Binder, Adobe Certified Instructor on Adobe InDesign
Updated: Nov 17, 2020. Works on InDesign CS4 and Later

Typesetting fractions is no fun, or at least it didn’t used to be. The introduction of OpenType fonts and the Glyphs panel were a great help, allowing point and click access to additional commonly used options:

InDesign CS4/CS5: The Glyphs Panel

But what if you need a fraction that isn’t included in the character set? You can manually superscript the numerator, kern the slash, and then go to work on the denominator. Or not! Wouldn’t it be cool if you could just type 1/2 and have it automatically format it as InDesign CS4/CS5: Sample 1/2 Fraction? With the right fonts, you can, and it’s easy! Here’s how:

  1. Assuming that the fractions appear in your body text paragraphs, begin by creating a new Paragraph Style called “Body Text” and assign your favorite OpenType face, size and style (in this example, I’m using Adobe Garamond Pro), but don’t click OK just yet:
    InDesign CS4/CS5: New Paragraph Style dialog box
  2. To add the automatic fraction formatting, first click on the GREP Style category in the New Paragraph Style dialog box, and then click the New GREP Style button at the bottom:
    InDesign CS4/CS5: GREP Style
  3. Change the To Text code to \d+/ \d+. (In English that means, look for one or more digits ( \d+) followed by a forward slash (/) followed by one or more digits ( \d+):
    InDesign CS4/CS5: Edit the GREP code to read d+/d+
  4. Add a character style to the string by chosing New Character Style from the Apply Style drop-down list:
    InDesign CS4/CS5: Create a New Character Style
  5. Give the new style a logical name like Fractions, and then click on OpenType Features category. Click to place a checkmark in front of Fractions:
    InDesign CS4/CS5: Set the OpenType Feature to Fractions
  6. Click OK twice to close the open dialog boxes. Assign your new paragraph style to a sample paragraph and start typing numbers, followed by a slash, followed by more numbers. It’s magical!
    InDesign CS4/CS5: Automatic Fractions

AUTHOR’S NOTES

For this sequence to work you need to a.) use InDesign CS4 or later and b.) use an OpenType font that offers numerators and denominators. Take Adobe Garamond Pro, for example. If you open the Glyphs panel (Type > Glyphs), you can show both the numerators:

ss_002

and the denominators:

Adobe InDesign: Glyphs panel shows denominators

However, if you change the font (on the bottom row of the Glyphs panel) to Birch (another OpenType font):

Adobe InDesign: Change the font to Birch

You will notice that it does not have numerators and denominators, therefore, the technique shown above will not work.

Adobe InDesign: Birch, an OpenType font, doesn't offer numerators or denominators

Also, the GREP won’t work for you if you have a whole number, followed by a fraction (i.e., one and a half cups of flour typeset in fraction form). In that situation, add a space—spacebar, thin space, hair space—between the whole number and the numerator. Or, if you are sure that all of your fractions are single digits, you can just change the GREP from \d+/\d+ to just \d/\d to tell InDesign to only match a single digit numerator and denominator. (The plus symbol aftr the \d matches one or more digits, which is why it grabs the leading digit.)

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12 thoughts on “Adobe InDesign: Need Fractions?

  1. Hi Barb
    To be sure don’t find date like this 12/05/70, you can write this regex:
    (?<!d)(?<!d/)d+/d+(?!/d)(?!d)
    (cf. M. Murphy, Adobe InDesign Style)
    Bonne journée

    1. Nice catch, Laurent. I would have been caught by surprise at the first date appearing in my document. Thank you for the comment et bonne journée à vous, aussi.

  2. We have to make fractions in our textbooks with a horizontal line dividing the numerator and denominator. It’s a real pain! Do you have any suggestions other than what we’re doing now: creating them and then using them as in-line graphics…

    I haven’t been able to find a font that does this.

    Thanks!

    1. Excellent question, Annette. The OpenType options are geared towards slash fractions. You could set up your horizontal fractions as text by using a combination of kerning, baseline shift and an en dash, but it’s still pretty darn tedious. How about collecting all of your fractions graphics into an InDesign Library item? At least it’s visual, and you could drag and drop them into place. Or, create all of the horizontal fractions as text once, and then put them in the library? There’s no perfect solution for you yet. 🙁

  3. Hi followed this to the letter using your preferred font and everything. I am getting all whole numbers formatted as numerators.

    1. Hi MQ:

      Then something is likely wrong with the GREP, which I can’t repost in a reply because WordPress messes with it. I think your best bet is to post this as a new question on the Adobe InDesign community forum. That way you can include screenshots and we can see exactly what you are doing. Feel free to reference this post, just as you did in your question here.

      It should be an easy fix.
      https://forums.adobe.com/community/indesign

      ~Barb