How to Change the Font Size in Slack on Desktop and Mobile

To zoom in on Slack and make the text bigger, press Cmd and + on a Mac or Ctrl and + on Windows and Linux. To zoom out, press Cmd and - or Ctrl and -, and Cmd and 0 or Ctrl and 0 goes back to the normal size. To keep a size, open Preferences, Accessibility, and pick a level under Zoom. On iPhone and Android, Slack has no text size setting of its own; it follows the font size you set on the phone. None of this changes what your coworkers see. Slack messages have no font size option, so bold text or a canvas heading is the way to make a line stand out.

The free Markdown to Slack converter shows how bold, lists and code look in Slack before you post.

Make Slack text bigger or smaller, by device

On some keyboards the + key needs Shift, so Cmd+Shift+= does the same as Cmd and +. Cmd+0 or Ctrl+0 puts the desktop app back at its normal size.

Set a zoom level in Slack preferences

Slack's help center gives these steps for the desktop app:

• Click your profile picture in the sidebar.
• Select Preferences.
• Click Accessibility.
• Under Zoom, select your zoom level.

The zoom setting scales everything in Slack: messages, the sidebar, names and buttons. It is only in the desktop app. We opened Preferences, Accessibility in Slack's web app on 3 October 2026, and it has display, alt text, keyboard and screen reader options but no Zoom:



In a browser, use the keyboard shortcut instead. It changes the browser's own zoom for that site.

The desktop app keeps one zoom level for the whole app, not one per workspace. On our Mac (Slack 4.52.171) it is stored in Slack's own settings file:

$ python3 -c "import json,os; print(json.load(open(os.path.expanduser('~/Library/Application Support/Slack/storage/root-state.json')))['settings']['zoomLevel'])"
0

0 is the normal size. If Slack looks too big or too small in every workspace at once, this is the value that changed, and Cmd+0 or Ctrl+0 sets it back.

If the text is fine but the layout feels cramped or too spread out, try the message theme under Preferences, Messages & media. Compact fits more messages on the screen and hides profile photos; Clean is the default.

Change the font in Slack

Slack also lets you pick a different font. On desktop, click your profile picture, choose Preferences, then Appearance, and choose an option under Font. Slack says this works on desktop and in the browser, for Latin-based languages, and you set it for each workspace you are in. It changes the typeface, not the size; for size, use zoom. The 10 fonts in that menu, and which font Slack uses by default, are in what font Slack uses.

Slack font size on iPhone and Android

The Slack mobile apps do not have a zoom setting. Slack's help center says the app matches the font size in your device settings:

• iPhone and iPad: Settings, Display & Brightness, Text Size, and drag the slider. For sizes beyond the slider, go to Settings, Accessibility, Display & Text Size, Larger Text.

• Android: Settings, Display, Font size. The name can differ by phone maker; search Settings for "font size".

Close and reopen Slack if the text does not change right away. This changes the text size in every app on the phone, not only Slack.

Can you change the font size of a Slack message?

No. There is no font size button in the Slack message field, and markdown headings with a # do not work in messages. Everyone reads your message at the size they chose. To make a line stand out anyway:

• Bold a short first line, like a title, then write the rest below it. Select the text and press Cmd+B or Ctrl+B.

• Use a canvas. Slack canvases support real headings, so a long update with sections reads better there. See Slack canvas vs lists.

• In a bot or workflow message, use a header block. Block Kit's header block shows a heavier title line:

{
  "blocks": [
    { "type": "header", "text": { "type": "plain_text", "text": "Release 2.4 is live" } },
    { "type": "section", "text": { "type": "mrkdwn", "text": "Dark mode, faster search, and 12 bug fixes." } }
  ]
}

We posted that message to ourselves on 3 October 2026, together with a normal message that starts with #, then deleted both:

In Slack's web app the header did not come out bigger. Its capital letters measured the same 21 pixels tall in our screenshot as the bold phrase below it, and the page styles both at 15px, the header at weight 900 and bold text at 700. The # line stayed plain text. So a header block makes a title heavier, not larger. The header text must be plain_text, so no bold or links inside it. To convert a markdown document with # headings into something Slack shows well, use our Markdown to Slack converter; it turns headings into bold lines.

Emoji follow a different rule: an emoji sent with no text shows large. See how to make Slack emoji bigger.

Slack text too small or too big after an update

• The zoom level changed. Pressing Cmd and - by accident is common. Press Cmd+0 (Ctrl+0) or check Preferences, Accessibility, Zoom.

• A new monitor or display scaling. On Windows, Slack follows Settings, System, Display, Scale. On a Mac, check System Settings, Displays.

• Browser zoom. In a browser, the zoom is per site. Reset it in the browser's menu.

• Phone text size. On mobile, check the device text size above.

More shortcuts, including the formatting keys, are in our Slack keyboard shortcuts guide.

FAQ

How do I make Slack text bigger? Press Cmd and + on a Mac or Ctrl and + on Windows and Linux, or set Zoom in Preferences, Accessibility in the desktop app.

How do I zoom out in Slack? Press Cmd and - or Ctrl and -. Cmd+0 or Ctrl+0 resets the size.

Why can't I find the Zoom setting in Slack? It is only in the desktop app. Slack in a browser has no Zoom option under Accessibility, so use the keyboard shortcut.

How do I change the font size in the Slack app on my phone? Change the text size in your phone's settings. Slack follows it.