How to Turn On Spell Check in Microsoft Word

Spell check is one of Word's most reliable features — but it doesn't always behave the way you expect. Sometimes it's quietly disabled. Sometimes it works in one document but not another. Understanding how Word's spell check actually works helps you troubleshoot it faster and configure it the way you actually want.

How Spell Check Works in Word

Microsoft Word uses two overlapping systems to catch errors:

• Automatic spell check — flags misspelled words in real time with a red underline as you type
• Manual spell check — a full document review you trigger yourself, usually via the Review tab or the F7 shortcut

Both rely on the same underlying dictionary and proofing engine, but they're controlled by separate settings. You can have one enabled without the other.

Word also separates spelling from grammar checking. They're toggled independently, so it's possible to have grammar checking on while spell check is off — or vice versa.

Turning On Spell Check: The Main Settings Path

The primary spell check controls live in Word's Options menu:

1. Click File → Options
2. Select Proofing from the left sidebar
3. Under When correcting spelling and grammar in Word, check the boxes you want enabled:
   • ✅ Check spelling as you type
   • ✅ Mark grammar errors as you type
   • ✅ Frequently confused words (optional)

Click OK and Word will immediately begin underlining errors in your document.

On Mac, the path is slightly different:

1. Word menu → Preferences
2. Click Spelling & Grammar
3. Enable Check spelling as you type

Why Spell Check Might Be Off — Or Appear Broken

This is where most confusion comes from. There are several independent reasons spell check can stop working:

The Document Language Is Set Incorrectly

Word's proofing tools are language-specific. If a section of text is tagged as a language that doesn't match your installed dictionary — or is set to "Do not check spelling or grammar" — Word skips it entirely.

To check this:

• Select all text (Ctrl+A)
• Go to Review → Language → Set Proofing Language
• Make sure the correct language is selected and that "Do not check spelling or grammar" is unchecked

This is one of the most common causes of spell check seemingly working in some parts of a document but not others.

The Document Was Created With Spell Check Disabled

Word stores spell check preferences at the document level, not just at the application level. A document created or edited by someone who had spell check turned off can carry that setting with it — even if your own Word installation has spell check enabled globally.

The fix is the same: go to Review → Language → Set Proofing Language, and make sure the "Do not check" box is cleared.

AutoCorrect and Spell Check Are Different Things

AutoCorrect automatically fixes common typos as you type (changing "teh" to "the"). Spell check flags words it doesn't recognize. They're separate systems. Turning one on doesn't affect the other.

AutoCorrect settings are found under File → Options → Proofing → AutoCorrect Options.

Running a Manual Spell Check

If you prefer to review errors in one pass rather than seeing them flagged in real time:

• Press F7, or
• Go to Review → Spelling & Grammar

Word will step through each flagged issue and offer suggestions. This is useful in documents where constant red underlining is distracting, like when drafting or brainstorming.

Spell Check Settings That Vary by Setup 🔍

One thing worth noting: custom dictionaries travel with your Word installation, not with the document. If you add technical terms or proper nouns to your custom dictionary on one machine, those words won't be recognized on a different computer unless the dictionary is transferred.

Word Version and Platform Differences

The core spell check functionality is consistent across modern versions of Word, but the interface and available options vary:

• Word for Microsoft 365 and Word 2021/2019 have the most complete proofing settings, including Editor (Microsoft's expanded grammar and style tool)
• Word Online (browser-based) has more limited proofing options and relies partly on the browser's own spell check
• Word for Mac follows the same logic but uses macOS system dictionaries for some functions
• Word on mobile (iOS/Android) has basic spell check but fewer configuration options compared to desktop

If you're working across devices, the experience won't be identical — and settings changed in one environment don't always carry over to another. ✏️

When Words Keep Getting Flagged Incorrectly

If correct words are consistently marked as errors — especially technical terms, brand names, or industry-specific vocabulary — spell check isn't broken. Word simply doesn't recognize those words.

The fix is to add them to your custom dictionary:

• Right-click the flagged word
• Select Add to Dictionary

This tells Word to treat that word as correct from that point forward, across all documents on that installation.

How much this matters depends heavily on your field. Someone writing general business emails has a very different experience with Word's default dictionary than someone writing software documentation, medical notes, or legal briefs. The gap between Word's built-in dictionary and the vocabulary of specialized work is something each user has to close on their own terms.