Where to find the font size setting in Outlook
The default font size in Outlook lives in the message format settings, not in the general preferences. On Windows, open Outlook and go to File > Options > Mail. On the left side, click Stationery and Fonts. You'll see separate sections for composing new messages, replying to messages, and reading messages — each can have its own font size.
On Mac, the path is different. Open Outlook, then go to Outlook > Preferences > Composing. Look for the font and size options under the message format section. Mac users have fewer granular controls than Windows users, but the basic size adjustment works the same way.
The font size you set here becomes the default every time you start a new message. It does not change the size of messages you've already received or sent — only what Outlook uses when you begin typing something new.
Key Takeaways
- On Windows, the font size setting is in File > Options > Mail > Stationery and Fonts, with separate controls for new messages, replies, and reading pane.
- On Mac, go to Outlook > Preferences > Composing to adjust the default font size for new messages.
- You can set different font sizes for composing new messages and replying to existing ones.
- Changing the default font size does not affect messages you've already written or received.
Setting a different size for replies versus new messages
Outlook lets you use one font size when you're writing a brand new message and a different size when you're replying to someone. This is useful if you want replies to match the original message's formatting but new messages to stand out with a larger or smaller size.
On Windows, in the Stationery and Fonts window, you'll see three sections: "New Mail Messages," "Replying or Forwarding Messages," and "Composing Messages." Each has its own font size dropdown. Set them independently — changing one does not affect the others.
On Mac, the controls are more limited. You set one default for composing, and replies typically inherit the original message's formatting rather than using a separate default. If you want replies in a specific size, you'll need to adjust them manually each time.
Choosing a readable font size
Common default sizes in Outlook are 11 point and 12 point. Eleven-point is the standard for business email and fits more text on screen without scrolling. Twelve-point is slightly larger and easier to read on smaller monitors or for people who prefer larger text.
If you're sending messages to people on mobile devices, keep in mind that font size can render differently depending on their email client and screen size. A 12-point font on your desktop may appear smaller on a phone. Testing a message to yourself on your phone before settling on a size can help you see how it actually looks to recipients.
If Outlook's preset sizes don't match what you want, some versions allow you to type a custom size directly into the dropdown field. Try typing a number like 13 or 14 and pressing Enter — if your version supports it, Outlook will accept the custom value.
Why your font size might not be changing
If you've set a default font size but new messages still appear in a different size, check whether you have a signature or template applied. Signatures often carry their own formatting, and Outlook may prioritize the signature's font size over your default. Edit your signature in File > Options > Mail > Signatures and make sure it's using the size you want.
Another common issue is that Outlook sometimes defaults to HTML format for new messages, which can override your plain-text font settings. If you prefer plain text, go to File > Options > Mail > Compose Messages and select "Compose messages in plain text format." This forces Outlook to use your chosen font size consistently.
On Mac, if the font size isn't sticking, try closing and reopening Outlook completely. Preferences sometimes don't take effect until the application restarts. If the problem persists, check whether you're using Outlook in a corporate environment with group policies — your IT department may have locked the font size setting.
Changing font size for the reading pane only
If you want to keep your outgoing messages at one size but make received messages easier to read, you can adjust the reading pane font separately. On Windows, in the Stationery and Fonts window, look for the "Composing and Reading Plain Text" section and adjust the size there.
This setting affects how messages appear when you're reading them, not how you write them. It's useful if you receive a lot of messages in a small default font and want to enlarge them without changing what size you send out.
Resetting to Outlook's default if changes aren't working
If you've made changes and Outlook is behaving unpredictably, you can reset the font settings to factory defaults. On Windows, go back to File > Options > Mail > Stationery and Fonts and look for a "Reset" button at the bottom of the dialog. Click it to restore Outlook's original font settings, then adjust them again from scratch.
On Mac, there's no built-in reset button. Instead, quit Outlook completely, then open Finder and go to your home folder. Press Command+Shift+Period to show hidden files. Navigate to Library > Preferences and look for a file named something like "com.microsoft.Outlook.plist". Moving this file to the trash and restarting Outlook will reset all preferences, including fonts. Be aware this will also reset other settings you've customized.
Frequently Asked Questions
Will changing my default font size affect emails I've already sent?
No. The default font size only applies to new messages you write going forward. Messages you've already sent keep their original formatting, and messages you receive are not affected by your default settings.
Can I set different font sizes for different email accounts?
On Windows, the font size settings apply to all accounts in your Outlook profile. You cannot set a different default for each account from the main settings. However, you can create separate signatures for each account and give each signature its own font size, which will apply when you use that account.
Why does my font size look different on my phone than on my computer?
Email clients on phones render fonts differently than desktop Outlook. A 12-point font on your computer may appear smaller or larger on a mobile device depending on the phone's email app and screen size. Test messages on your phone to see how they actually appear to recipients.
Does changing the default font size in Outlook affect other Microsoft Office programs?
No. Word, Excel, and PowerPoint have their own separate default font settings. Changing the font size in Outlook does not change defaults in any other Office application.
What if I want to use a different font, not just a different size?
In the same Stationery and Fonts window where you change the size, you can also change the font itself. Click the font dropdown to choose from installed fonts like Arial, Calibri, or Times New Roman. You can set different fonts for new messages and replies, just like with size.