How to Adjust Subscript and Superscript in FontForge

Adjusting subscript and superscript metrics in FontForge ensures that applications render small-scale text with accurate baseline positioning and proportional sizing. This guide explains how to locate the OS/2 metric settings in FontForge and modify the scaling and offset parameters to achieve balanced typography.

Accessing Font Information

  1. Open your font project in FontForge.
  2. Click on the Element menu in the top navigation bar.
  3. Select Font Info from the dropdown menu (or press Ctrl+Shift+F on Windows/Linux, Cmd+Shift+F on macOS).
  1. In the Font Info dialog, look at the left sidebar listing the configuration categories.
  2. Click on the OS/2 category to expand its options.
  3. Select the Sub/Superscript sub-tab.

Adjusting the Metrics

The panel is divided into sections for both Subscript and Superscript. Each section contains four main parameters that dictate how applications scale and position synthetic or standard sub/superscript glyphs:

  • X Size: The horizontal scaling width of the glyphs, typically set around 65% to 75% of the font's standard em size.
  • Y Size: The vertical scaling height of the glyphs, generally matching the X Size to maintain proportions.
  • X Offset: The horizontal shift applied to the glyph. In most standard fonts, this remains at 0 so the character does not drift sideways.
  • Y Offset: The vertical displacement relative to the baseline.
    • For Subscript, set a negative value or a low baseline-relative value (depending on standard OS targets) to pull the characters below the baseline.
    • For Superscript, set a positive value to elevate the characters above the mean line or cap height.

Saving the Changes

  1. Click OK at the bottom of the Font Info dialog to apply your adjustments.
  2. Save your font database (File > Save).
  3. Re-generate the font binaries (File > Generate Fonts) to test the updated metrics in your target applications or browsers.