Change font size before you write a message

The fastest way to set a larger or smaller font for a single message is to adjust the size before you start typing. In Outlook on Windows, open a new message, then look for the font size dropdown in the toolbar — it usually shows a number like "11" or "12". Click it and pick the size you want. On Mac, the same dropdown appears in the message composition toolbar.

This change applies only to the message you are currently writing. When you send it and start a new message, Outlook reverts to your default font size. If you find yourself changing the size every time, you may want to set a new default instead.

Set a default font size for all new messages

To make a larger or smaller font your permanent starting point, you need to change your default message format settings. On Windows, go to File > Options > Mail > Stationery and Fonts. You will see separate sections for composing new messages, replying, and forwarding. Click Fonts under "New Mail Messages" to open the font dialog.

In that dialog, select the font name you want, then set the size in the "Size" field. Click OK twice to save. From that point forward, every new message you write will open in that font size. Replies and forwards use their own default, which you can change the same way by clicking Fonts under "Replying or Forwarding Messages".

On Mac, open Outlook > Preferences > Composing, then click Fonts. Select your preferred size and click OK. Mac Outlook applies this default to new messages, replies, and forwards all at once.

Key Takeaways

  • You can change the font size for a single message using the font size dropdown in the message toolbar before you start typing.
  • To set a permanent default font size on Windows, go to File > Options > Mail > Stationery and Fonts, then click Fonts under "New Mail Messages".
  • On Mac, open Outlook > Preferences > Composing and click Fonts to set your default size for all new messages.
  • Windows Outlook lets you set different default sizes for new messages versus replies, but Mac applies one default to all message types.

Change font size in messages you receive

If an incoming message is too small or too large to read comfortably, you can zoom in or out without changing the message itself. On Windows, use Ctrl and the scroll wheel on your mouse, or press Ctrl and + to enlarge or Ctrl and - to shrink. On Mac, hold Command and scroll, or press Command and + or Command and -.

This zoom applies only to the message you are viewing right now. When you open a different message, it returns to normal size. If you want to permanently increase the size of text in all received messages, you can change your reading pane font in settings, though this option is more limited than the compose settings.

Adjust font size in the reading pane

On Windows, you can set a default font size for how messages appear in the reading pane. Go to File > Options > Mail > Stationery and Fonts, then click Fonts under "Composing Messages". The font you choose here also affects how received messages display, though the sender's original formatting may override your choice depending on whether they sent the message as plain text or HTML.

Mac does not offer a separate reading pane font setting. Your best option is to use the zoom controls (Command and scroll) when a message is too small, or to ask senders to use a larger font in their messages.

Why the sender's font might override your settings

When someone sends you a message formatted as HTML (the default in Outlook), their font size choice usually displays as they intended, even if you have set a different default. This is by design — the sender's formatting takes priority over your reading preferences. Plain text messages, by contrast, always display in whatever font and size you have set for plain text viewing.

If a sender consistently uses a font size that is hard for you to read, ask them to change their default settings on their end. You can also use the zoom controls in the reading pane as a temporary fix for any single message.

Font size on Outlook mobile apps

Outlook on iPhone and Android does not offer a compose-time font size picker. Instead, the app uses the font size you set in your device's accessibility settings. On iPhone, go to Settings > Accessibility > Display & Text Size and adjust "Larger Accessibility Sizes" or "Larger Text". On Android, go to Settings > Accessibility > Display and look for text size or font size options.

These device-level changes affect Outlook and all other apps on your phone. If you want to change font size only in Outlook on desktop, use the methods described above instead.

Frequently Asked Questions

Does changing my default font size affect messages I have already sent?

No. Your default font size applies only to new messages you write from that point forward. Messages you have already sent keep their original formatting. Recipients see what you sent them, not your current settings.

Why does my font size change back to the default after I send a message?

Outlook resets to your default font size for each new message. If you changed the size for a single message and then started a new one, the new message uses your default setting. This is normal behavior and prevents you from accidentally sending messages in an unintended size.

Can I set different font sizes for different recipients?

Outlook does not have a built-in way to set font size by recipient. You would need to manually change the font size each time you write to someone who prefers a different size. Some users create separate signatures with different fonts and sizes, then manually select the right one for each message.

Does zooming in on a received message change how it looks to the sender?

No. Zooming affects only what you see on your screen. The sender has no way to know you zoomed in or out, and the message itself is not changed. When you open a different message, the zoom resets.