Why font ligatures change how letter pairs look
See why pairs like fi and fl look joined in some fonts, compare them in your own text, and learn how to control ligatures in an app.
Pairs such as fi and fl can look joined, tightly spaced, or almost like a single character in one font, then appear as separate letters in another. That difference is usually a font feature called a ligature, not a typo or missing character.
Use the Installed Fonts tool to compare how different fonts display your own text. Then check the typography options in the app where you noticed the change.
Compare letter pairs in different fonts
- Open Installed Fonts and enter a sample that includes pairs such as
fi,fl,ffi, andffl. - Compare the preview in several typefaces. Keep the text and size the same so you can focus on the letter shapes.
- Look for a joined form, a shared stroke, or unusually close spacing. Some fonts use a special combined glyph for certain pairs.
- Open the same sample in the app where you saw the difference. If that app offers a ligature setting, compare the text with the setting on and off.
The font preview is useful for comparing appearance, but it may not offer the same typography controls as your document, design, or code app. The app's text-shaping behavior determines which font features it uses.
What the result means
The pair looks joined in one font
The typeface may include a ligature for that sequence. A ligature is a single drawn glyph used to display two or more underlying characters together. The text is still made of the original letters. For example, a visible fi ligature normally remains an f followed by an i for editing, searching, and copying.
Designers use ligatures to avoid awkward collisions or improve the flow of a typeface. In some styles, the top of the f can sit close to the dot of the i. A custom combined shape can make the pair look more balanced.
The pair looks different only in one app
The app may be applying a font feature that another app ignores, or the app may have its own ligature setting. Text-shaping engines can also differ in how they apply font features. The font itself may be the same while the displayed result changes.
The pair stays separate in every preview
The chosen fonts may not include a ligature for that sequence, or the preview may not apply that optional feature. Not every font has ligatures for every pair. A font can support fi and fl without supporting ct or st.
How to control ligatures
- Check the app's typography options. Select the text and look for a setting called Ligatures, often in a font, typography, or advanced text panel. The location and available choices depend on the app.
- Choose the feature that matches your goal. Standard ligatures cover common pairs such as
fiandfl. Discretionary ligatures are more decorative and may change less common combinations. Some apps offer a setting to turn ligatures off. - Try another font before changing the text. If a pair looks too ornate or hard to read, switch to a typeface with simpler letterforms. This is often easier than manually replacing or spacing characters.
- Check the final output. Review a PDF, print preview, or exported image if that is where the text will be used. The exported result can differ from the editing view if the font is substituted or the app handles font features differently.
Windows 11 and macOS do not have one universal system setting that turns ligatures on or off in every app. The controls belong to the application, and some apps do not expose them. If you cannot find a ligature option, try a different font or check the app's own help for its typography controls.
Why ligatures do not change the words
A ligature changes how letters are drawn, not what the text says. A word containing fi still contains those two characters even when the font displays them with one joined shape. You can usually place the cursor between them, select them, or find the word using the ordinary spelling.
This differs from replacing letters with a special symbol or image. A ligature is a font feature that the text renderer can apply while laying out ordinary text. If a document opens in an app that does not use the feature, the same letters may appear separately.
For body text, a subtle ligature can make a font feel smoother. For a logo, a title, or a code sample where exact character shapes matter, compare the output in the app and format where it will be used.
