How to Change Font Size in Outlook: Complete Guide for 365, 2019, 2016 & Mobile

You know that frustration when an important email looks microscopic? Or when your reply suddenly shouts at people in 14-point font? Changing font size in Outlook shouldn't be this confusing. I remember wasting 20 minutes trying to fix my colleague's zoomed-out inbox last month - turns out she'd accidentally changed her DPI settings. This guide fixes those headaches for good.

Pro Tip: Outlook stores font settings in THREE different places. That's why changing one screen doesn't affect others. We'll crack them all.

Why Messing With Outlook Fonts Gets Tricky

Outlook handles fonts differently than Word or PowerPoint. There's no universal slider because:

  • Reading pane ≠ composition window
  • Windows scaling fights with Outlook's settings
  • HTML vs Plain Text emails render differently

Just last Tuesday, my client panicked because his signature font changed after a Windows update. Classic Outlook quirk.

Quick Fixes vs Permanent Solutions

What You Want to Change Quick Method Permanent Method Works For
Reading emails Zoom slider (bottom right) Default mail format All Outlook versions
Writing new emails Formatting toolbar Stationery & Fonts 2013, 2016, 2019, 2021
Folder/menu text Windows scaling Registry edit Windows only Advanced users

Changing Font Size While Reading Emails

When emails look too small in your reading pane:

Method 1: The Zoom Slider (Fastest Fix)

Look at Outlook's bottom-right corner. See that percentage? Drag that slider left/right. Works instantly.

Annoyance Alert: Resets every time you open a new email. Drives me nuts when reading long threads.

Method 2: Permanent Reading Font Adjustment
  1. Go to File > Options
  2. Select "Mail" > "Stationery and Fonts"
  3. Click "Font" under Composing and reading plain text messages
  4. Choose size + font > OK x 3

Warning: Only affects plain text emails. HTML messages ignore this.

The Mobile Workaround

On Outlook for iOS/Android:

  • Pinch zoom on any email
  • Go to Settings > Mail > Message Text Size

Funny story - my aunt thought her phone was broken because pinching stopped working. She'd accidentally enabled "Single Finger Zoom" in accessibility settings.

Changing Default Font for New Emails

This changes how your emails look when recipients open them:

Critical: These settings DON'T apply when replying/forwarding. Outlook inherits the original email's formatting.

Outlook Version Steps to Change Composition Font Special Notes
Outlook 365 (Current)
  1. New Email > Format Text tab
  2. Click Font Dialog box (tiny arrow)
  3. Set font/size > "Set As Default"
Must select "All documents based on Normal template"
Outlook 2013
  1. File > Options > Mail
  2. Stationery and Fonts > Fonts
  3. Set "When composing new messages"
HTML format recommended
Outlook Web (OWA)
  1. New message > Formatting toolbar
  2. Choose font/size
  3. Click "Save as default" (below font list)
Only available in new OWA interface

Why this fails sometimes: If you choose Calibri 11pt but emails still send as 10pt, check your default mail format (File > Options > Mail > Compose messages in: HTML). Plain text overrides font choices.

Fixing Tiny Interface Text (Folders/Menus)

When folder names or menu text is microscopic:

Option 1: Windows Scaling (Safest)

  1. Right-click desktop > Display settings
  2. Adjust "Scale and layout" percentage
  3. Sign out then back in

Option 2: Outlook-Specific Fix Windows only

  1. Close Outlook
  2. Win+R > regedit
  3. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
  4. Create new DWORD "FontScale"
  5. Set value: 112 = 175%, 96 = 150% (calculate: desired % × 96)

Personal gripe: Microsoft should add this to settings instead of making us hack the registry.

Font Size Troubleshooting Checklist

When nothing works:

  • ✅ Check email format (HTML/Rich Text/Plain)
  • ✅ Verify default stationery isn't overriding
  • ✅ Disable "Use Microsoft Word to edit messages"
  • ✅ Update graphics drivers (affects rendering)
  • ✅ Try Safe Mode: Win+R > outlook.exe /safe

FAQs: Real User Questions Answered

Why does font size change when replying?

Outlook copies the original message's formatting. To override:

  1. File > Options > Mail
  2. Under Replies and forwards, choose "Reply using..."
  3. Select "HTML" or "Plain Text" consistently

Can I change font size for all incoming emails?

Yes, but it's buried:

  1. File > Options > Mail
  2. Click Stationery and Fonts
  3. Under "Composing and reading plain text messages", click Font

Limitation: Doesn't work for HTML emails (most newsletters)

Why do fonts look different on mobile?

Phones override email CSS. Test with:

  • Minimum 14px for body text
  • Avoid fancy fonts (use Arial/Helvetica)
  • Add line-height: 1.5 in HTML code

How to permanently increase signature font?

Signatures store their own formatting:

  1. Signature > Edit signature
  2. Highlight text > choose font size
  3. Save BEFORE closing

Note: If it reverts, your signature might be stored in Office 365 admin center.

Pro Tips I Learned the Hard Way

  • Accessibility win: Change default to 12pt minimum for older colleagues
  • Corporate policy hack: If admin locks settings, use Word templates
  • Zoom memory trick: Hold Ctrl+scroll wheel to temporarily zoom

Debugging horror story: A client's font kept shrinking because their mouse scroll wheel was broken. Always check hardware!

The Outlook Version Cheat Sheet

Task Outlook 365 Outlook 2016 Outlook Web Outlook Mobile
Reading pane zoom Bottom slider Bottom slider Ctrl +/- Pinch zoom
Default new email font Format Text > Font dialog Options > Mail > Stationery Save as default Not possible
Reply font control Options > Mail > Replies Same as 365 Settings > Compose No override

When All Else Fails: Nuclear Options

Desperate measures for stubborn Outlook font issues:

  1. Reset view: View tab > Current View > Reset View
  2. Delete registry key: Backup then delete HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\View
  3. New Outlook profile: Control Panel > Mail > Show Profiles > Add

Confession: I rebuilt my Outlook profile 3 times last year chasing a font bug. Sometimes it's fastest.

Changing font size on Outlook feels like solving a puzzle with missing pieces. But once you know where Microsoft hides the settings, it's manageable. The key is understanding Outlook treats reading, writing, and replying as separate activities - each with its own font rules. Now go fix those microscopic emails!

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