Spell check is on by default in Word, but you may need to turn it back on if you've disabled it
Spell check in Microsoft Word runs automatically as you type. Red squiggly lines appear under words the program doesn't recognize — misspellings, proper nouns, and technical terms. If you don't see these lines, spell check is either turned off or set to hide errors until you run a manual check. Turning it back on takes one or two clicks, depending on which version of Word you use and what you want to change.
The steps differ slightly between Word on Windows, Word on Mac, and Word Online. All three versions let you toggle spell check on and off, and all three let you ignore certain words or add them to your dictionary so they stop appearing as errors.
Key Takeaways
- Red squiggly lines under words mean spell check is on; if you see none, check the Review tab to turn it back on.
- In Word for Windows and Mac, go to File > Options (or Preferences on Mac) and search for "spelling" to find the toggle.
- In Word Online, spell check cannot be turned off — errors always appear, though you can ignore specific words.
- Right-clicking a red-underlined word lets you accept a suggestion, ignore it once, or add it to your dictionary permanently.
- Grammar check (blue squiggly lines) is separate from spell check and has its own toggle in the same menu.
How to turn on spell check in Word for Windows
Open Word and go to the File menu in the top left. Click Options at the bottom of the menu. In the Options window, click Proofing on the left side.
Under the "Spelling" section, look for the box labeled "Check spelling as you type" and make sure it is checked. If the box is empty, click it to turn spell check back on. You'll see the checkmark appear. Click OK at the bottom of the window to save the change.
Red squiggly lines should now appear under misspelled words as you type. If they don't show up immediately, try typing a word you know is misspelled (like "teh" instead of "the") to confirm spell check is working.
How to turn on spell check in Word for Mac
Open Word and click Word in the menu bar at the top. Select Preferences from the dropdown menu. In the Preferences window, click Spelling and Grammar.
Look for the option labeled "Check spelling while typing" and make sure the checkbox next to it is filled. If it's empty, click it to enable spell check. Close the Preferences window by clicking the red button in the top left corner.
Spell check will now run as you type. Like Word for Windows, you can test it by typing a misspelled word to see the red squiggly line appear.
How spell check works in Word Online
Word Online (the browser version you access through Office.com or OneDrive) runs spell check automatically and does not have an option to turn it off. Red squiggly lines appear under misspelled words as you type, just like the desktop versions.
If you want to hide the visual indicators temporarily, you can ignore individual words or run a full spell check from the Review tab at the top of the document. Click Spelling to open the spell check pane, which shows flagged words one at a time and lets you accept suggestions or skip them.
What to do when spell check flags a word you know is correct
Right-click any red-underlined word to see a menu of options. If the word is spelled correctly but Word doesn't recognize it (a name, a technical term, or a brand), you have two choices: Ignore All tells Word to stop flagging that word for the rest of the document, and Add to Dictionary
Use "Add to Dictionary" for words you use regularly, like your last name or the name of your company. Use "Ignore All" for words that are correct in this document but might not be in others — like a character name in a story, or a specialized term you're only using for this project.
If Word suggests a correction you want to use, click the suggestion from the menu and it will replace the misspelled word automatically.
Grammar check is separate from spell check
Spell check catches misspelled words. Grammar check catches sentence structure problems, punctuation errors, and word choice issues — it shows up as blue squiggly lines. Grammar check is turned on and off in the same menu as spell check, but it's a separate setting.
In Word for Windows, go to File > Options > Proofing and look for "Mark grammar errors as you type". In Word for Mac, go to Word > Preferences > Spelling and Grammar and look for "Check grammar while typing". Word Online runs grammar check automatically like spell check and cannot be disabled.
If you see blue squiggly lines but want to focus only on spelling, you can turn off grammar check while leaving spell check on. The two work independently.
Frequently Asked Questions
Why did spell check stop working in my document?
The most common reason is that spell check was accidentally turned off in Options (Windows) or Preferences (Mac). Go back to File > Options > Proofing (or Word > Preferences > Spelling and Grammar on Mac) and check the "Check spelling as you type" box. Another possibility is that you've added many words to your dictionary, so fewer errors appear — this is normal behavior.
Can I turn off spell check for just one document?
No — spell check is a program-wide setting that applies to all documents you open in Word. Turning it off affects every file. However, you can ignore specific words in a single document by right-clicking them and selecting "Ignore All," which only affects that document.
What's the difference between ignoring a word and adding it to the dictionary?
"Ignore All" stops Word from flagging that word in the current document only. "Add to Dictionary" tells Word the word is correct and stops flagging it in every document you write from that point forward. Use "Add to Dictionary" for words you'll use repeatedly, like your name or company name.
Does Word Online have the same spell check as the desktop version?
Word Online has spell check, but you cannot turn it off — it runs automatically. The desktop versions (Windows and Mac) let you toggle spell check on and off. Both versions show red squiggly lines and let you right-click to accept suggestions or add words to your dictionary.
Can I check spelling in other languages?
Yes. In Word for Windows, go to File > Options > Proofing and click "Language Settings" to add or change the language Word uses for spell check. In Word for Mac, go to Word > Preferences > Spelling and Grammar. You can set a default language or mark specific sections of text as a different language so Word checks them against the correct dictionary.