Change font size before you write

The fastest way to change font size in Outlook is to set it before you start typing. Open a new email, then look at the toolbar at the top of the compose window. You will see a box with a number in it — usually "11" — next to a dropdown arrow. Click that dropdown and select the size you want. Everything you type from that point will use that size.

This method works the same way whether you are using Outlook on Windows, Mac, or the web version. The toolbar looks slightly different depending on your version, but the font size selector is always near the formatting buttons (Bold, Italic, Underline).

If you do not see the toolbar, you may be in a simplified compose view. Look for a button that says "Options" or a three-dot menu icon, and click it to expand the full formatting toolbar.

Change font size in text you have already written

If you have already typed your email and want to change the size of some or all of it, highlight the text first. Click and drag your mouse across the words you want to change, or use Ctrl+A (Windows) or Command+A (Mac) to select everything in the email.

Once the text is highlighted, click the font size dropdown in the toolbar and choose a new size. The selected text will change immediately. You can do this as many times as you want — highlight different sections and change each one separately if you need different sizes in the same email.

Common sizes are 11 and 12 for regular body text, 14 or 16 for headings, and 9 or 10 if you need something smaller. If you do not see the exact size you want in the dropdown, you can type a custom number directly into the box.

Key Takeaways

  • The font size selector is a numbered box in the compose toolbar, next to a dropdown arrow, and works the same way in Outlook on Windows, Mac, and the web.
  • Set your font size before you start typing to avoid having to change it later, or highlight text after you have written it to change specific sections.
  • Standard sizes range from 9 to 16 points, but you can type any number into the box if you need a custom size.
  • If the toolbar is not visible, look for an Options button or three-dot menu to expand the full formatting options.

Where the font size button is in different Outlook versions

In Outlook on Windows (desktop version), the font size box sits in the main toolbar at the top of the compose window, usually between the font name dropdown and the Bold button. It shows a number like "11" with a small arrow next to it.

In Outlook on Mac, the layout is similar but the toolbar may wrap to two rows if your window is narrow. The font size selector is still in the formatting section, typically in the second row of buttons.

In Outlook on the web (Outlook.com or Microsoft 365 web access), the compose window is smaller and the toolbar is more compact. The font size dropdown is still there, but you may need to click the three-dot menu or "More options" button to see all formatting choices if your window is narrow.

If you cannot find the font size button at all, your version of Outlook may be in a simplified mode. Look for a settings icon or options menu and check whether there is a way to switch to a full compose view.

Set a default font size for all new emails

If you always want your emails in a larger or smaller size, you can change the default so you do not have to adjust it every time. In Outlook on Windows, go to File, then Options, then Mail, then Stationery and Fonts. Click the "Compose Font" button and select your preferred size, then click OK.

In Outlook on Mac, go to Outlook in the menu bar, then Preferences, then Fonts. Select the size you want for "Compose messages" and close the window.

In Outlook on the web, click the Settings icon (gear symbol) in the top right, then view all Outlook settings, then Mail, then Compose and reply. Look for the default font size option and change it there.

Once you set a default, every new email you create will start in that size. You can still change individual emails if you need to — the default only applies to new messages, not ones you have already started.

Troubleshooting: Font size reverts or does not change

If you change the font size but it keeps going back to the original size, you may have a signature or template that overrides your choice. Signatures in Outlook often have their own font size built in. Check whether your signature is being added to the email — if it is, the signature size may be taking over. You can edit your signature in Outlook settings to match your preferred size.

Another reason font size might not stick is if you are using a template or a reply to an email with formatted text. When you reply, Outlook sometimes keeps the original email's formatting. Highlight all the text in your reply and change the size manually, or start a new email instead of replying if the formatting is getting in the way.

If the font size button itself is greyed out or not responding, try closing the compose window and opening a new one. Sometimes the toolbar needs to refresh. If that does not work, restart Outlook entirely.

Why your recipient might see a different size than you do

The font size you set in Outlook is what you send, but the person reading your email might see it differently depending on their email program and their own settings. Some email clients override font sizes for readability, or the recipient might have zoomed their view in or out. This is normal and not something you can control.

If you are sending an email to someone with vision concerns and want to make sure they can read it, 14 or 16 point is a safe choice. Anything smaller than 11 point may be hard for some people to read on screen. If you are sending a formal document or something that needs to look a specific way, consider sending it as a PDF attachment instead of formatting it inside the email body.

Frequently Asked Questions

Can I make different paragraphs different sizes in the same email?

Yes. Highlight each paragraph or section separately and change its size using the font size dropdown. You can mix sizes freely — there is no limit to how many different sizes you can use in one email. Just remember that too many different sizes can make an email look unprofessional.

What is the largest font size Outlook lets me use?

Outlook does not have a hard limit on font size. The dropdown menu shows sizes up to 72 point, but you can type a larger number directly into the box if you need it. Most people never need anything larger than 28 or 36 point.

Does changing font size in Outlook affect how the email looks on a phone?

The size you set is preserved when someone opens your email on a phone, but phones often reflow text to fit the screen, which can make it look different. A size that looks good on a computer screen usually looks fine on a phone too, but there is no way to control exactly how it will appear on every device.

Why does my font size change back to 11 every time I close Outlook?

This usually means your default font size is still set to 11 in Outlook settings. Follow the steps in the "Set a default font size" section above to change it permanently. If you have already done that and it is still reverting, restart Outlook and check your settings again — sometimes changes do not save until you close and reopen the program.

Can I change font size in Outlook on my phone or tablet?

Outlook on mobile devices does not have a font size selector in the compose window. You can only change the size of text you are reading, not text you are writing. If you need to send an email in a specific font size, use Outlook on a computer instead.