font inspectorWhat font does ChatGPT use?
The chat interface is built to feel like part of your device, so it borrows the device’s own font. That differs from OpenAI’s marketing site, which has a custom typeface. We inspected the chat home screen.
Short answer: ChatGPT uses no web font for its interface. Text is set in the system font stack, so you see Segoe UI on Windows, San Francisco on a Mac and Roboto on Android. Only the KaTeX fonts for mathematics are downloaded.
System font stack
System font100%- CSS name
ui-sans-serif- Weights
- 400, 500, 600
- Sizes
- 24px · 18px · 17px · 16px · 14px
Sizes, weights and spacing by role
These are computed values from the live page, which is what the Font Inspector panel shows when you click each element.
| Role | Font | Size | Weight | Line height | Letter spacing |
|---|---|---|---|---|---|
| Headline | System font stack | 24px | 400 | 1.2 | normal |
| Body text | System font stack | 16px | 400 | 1.63 | normal |
| Navigation | System font stack | 16px | 400 | 1.5 | normal |
| Button | System font stack | 14px | 500 | 1 | normal |
The main font stack in the CSS:
font-family: -apple-system-body, ui-sans-serif, -apple-system, system-ui, "Segoe UI", Helvetica, "Apple Color Emoji", Arial, sans-serif, "Segoe UI Emoji", "Segoe UI Symbol";- Message text is 16px with a roomy line height of about 1.63, tuned for reading long answers.
- The only
@font-facerules on the page are the KaTeX math fonts, loaded for formulas in answers. - Compare OpenAI’s own website, which uses a custom typeface for its marketing pages.
Check any site yourself in one click.
Sites change their type without notice. Font Inspector shows the rendered font, size, weight and spacing of any text on chatgpt.com or anywhere else, and lists every font on the page. Free, no account.
About the fonts, and whether you can use them
System font stack
The stack opens with -apple-system-body, an Apple keyword that follows the user’s preferred text size on iOS, then ui-sans-serif and system-ui. On our Windows machine it rendered as Segoe UI.
Can you use it? Free to use: name the system fonts in your CSS and each device supplies its own. Nothing to license or download.
Finding a font does not license it. More in how to get a font you found, legally.
Get a similar look with a free font
This starter uses Inter, which is open source, with the sizes and spacing measured above. It is an approximation, not a copy of ChatGPT’s brand typeface.
/* Approximates the ChatGPT look with a free font */
body {
font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
}
h1 {
font-size: 1.5rem; /* 24px */
font-weight: 400;
line-height: 1.2;
}
p {
font-size: 1rem; /* 16px */
font-weight: 400;
line-height: 1.63;
}How we checked
We opened chatgpt.com in Chrome on November 5, 2026 and read the computed styles of its visible text: the declared font stack, the font actually rendered, and how much of the page’s text each family sets. That is the same data the Font Inspector extension shows under Fonts on this page. We re-check these pages periodically, and the date above shows the last inspection.
ChatGPT and its typefaces are trademarks of their respective owners. Font Inspector is not affiliated with ChatGPT.
Questions & answers
What font does ChatGPT use on its website?
ChatGPT uses no web font for its interface. Text is set in the system font stack, so you see Segoe UI on Windows, San Francisco on a Mac and Roboto on Android. Only the KaTeX fonts for mathematics are downloaded.
Can I use the ChatGPT font?
Free to use: name the system fonts in your CSS and each device supplies its own. Nothing to license or download.
How can I check what font ChatGPT uses myself?
Open chatgpt.com, then click any text with the Font Inspector extension, or right-click, choose Inspect and look at Rendered Fonts in the Computed tab. Sites change their typography, so checking the live page is the only way to be sure.