font inspectorWhat font does Substack use?
Substack keeps its own interface plain so that writers’ publications can have their own look. We inspected the logged-out home feed, not an individual newsletter, which can choose different fonts.
Short answer: Substack’s home feed is set almost entirely in the system font, with a serif called Cahuenga for its brand headlines.
System font stack
System font95%- CSS name
system-ui- Weights
- 400, 500, 600, 800
- Sizes
- 20px · 15px · 13px
Cahuenga
Self-hosted5%- CSS name
Cahuenga- Weights
- 500
- Sizes
- 32px · 24px
- Served from
- substackcdn.com
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 |
|---|---|---|---|---|---|
| Subheading | Cahuenga | 32px | 500 | 1.24 | normal |
| Body text | System font | 15px | 400 | 1.4 | normal |
The main font stack in the CSS:
font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;- The CSS also declares Spectral, a Google Fonts serif, which newsletters can use for their posts.
- We inspected on Windows, where
system-uiresolves to Segoe UI.
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 substack.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
Posts, notes and navigation in the feed use system-ui, the interface font of the visitor’s own device.
Can you use it? Free to use: put system-ui first in your font stack.
Cahuenga
A serif served from Substack’s own CDN and used for promotional headlines. It gives the brand a literary voice next to the neutral interface.
Can you use it? It is not a font we can point you to a license for. Newsreader and Source Serif 4 are free serifs that suit the same editorial tone.
On Google Fonts: Newsreader, Source Serif 4.
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 Newsreader, which is open source, with the sizes and spacing measured above. It is an approximation, not a copy of Substack’s brand typeface.
/* Approximates the Substack look with a free font */
body {
font-family: "Newsreader", Georgia, "Times New Roman", serif;
}
p {
font-size: 0.9375rem; /* 15px */
font-weight: 400;
line-height: 1.4;
}How we checked
We opened substack.com in Chrome on September 20, 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.
Substack and its typefaces are trademarks of their respective owners. Font Inspector is not affiliated with Substack.
Questions & answers
What font does Substack use on its website?+
Substack’s home feed is set almost entirely in the system font, with a serif called Cahuenga for its brand headlines.
Can I use the Substack font?+
Free to use: put system-ui first in your font stack.
How can I check what font Substack uses myself?+
Open substack.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.