Spell check in Word runs automatically as you type, marking errors with red squiggles

Microsoft Word checks your spelling in real time. As you write, any word it does not recognize appears with a red wavy underline. You do not have to open a menu or run a separate tool — it happens while you work. If you want to check an entire document at once, or if you want to see all errors together before fixing them, you can open the full spell-check window.

The location of spell check depends on which version of Word you use. In Word on Windows and Mac, the Spelling pane opens from the Review tab. In Word Online (the free version in your web browser), spell check works the same way but lives in a slightly different menu. The steps below cover the most common versions.

Key Takeaways

  • Red squiggles under words mean Word does not recognize them — right-click to see suggestions or add the word to your dictionary.
  • To check your whole document at once, go to the Review tab and select Spelling (or Spelling & Grammar on older versions).
  • Word Online spell check is found under the Editor button in the top toolbar, which also catches grammar issues.
  • You can add words you use regularly to your personal dictionary so Word stops marking them as errors.
  • Turning off spell check is possible but not recommended — it takes only a few clicks to ignore individual words instead.

How to fix a single misspelled word as you type

When you see a red squiggle under a word, right-click on it. A menu appears with spelling suggestions at the top. Click the correct spelling to replace the word when ready. If the word is spelled correctly but Word does not recognize it — a proper name, a technical term, or a brand name — you have two options: click "Ignore All" to skip that word everywhere in the document, or click "Add to Dictionary" to teach Word that this word is correct.

If you ignore a word, Word will still mark it as an error the next time you open the document. If you add it to your dictionary, Word remembers it and stops marking it as wrong in any document you write going forward. This is useful for names you use often, industry jargon, or words in other languages that you include regularly in your writing.

How to run spell check on your entire document at once

In Word on Windows: Open the Review tab at the top of the screen. Click the Spelling button (it looks like a checkmark with letters). The Spelling pane opens on the right side of your screen. Word shows you each error one at a time. For each error, you can click a suggestion to replace it, click "Ignore Once" to skip just that instance, click "Ignore All" to skip that word everywhere, or click "Add to Dictionary" to teach Word the word is correct.

In Word on Mac: Click the Review tab, then click Spelling. The same pane opens on the right. The buttons work the same way as Windows.

In Word Online: Click the Editor button in the top toolbar (it looks like a pencil on a page). The Editor pane opens on the right. Spelling issues appear under the Spelling section. Click each one to see suggestions, then click the suggestion you want or choose to ignore it.

The difference between spell check and grammar check

Spell check only looks at whether words are spelled correctly. Grammar check looks at sentence structure, punctuation, and word choice — things like whether you wrote "their" instead of "there," or whether you have a comma splice. In newer versions of Word (2019 and later on Windows, and recent versions on Mac), spell check and grammar check run together and are both called "Spelling" or "Editor."

In older versions of Word, you might see a button called "Spelling & Grammar" instead of just "Spelling." This runs both checks at the same time. The pane shows spelling errors in one color and grammar suggestions in another, so you can tell them apart.

How to add words to your personal dictionary

When you right-click a red-squiggled word and click "Add to Dictionary," Word saves that word to a file on your computer. The next time you use that word, it will not be marked as an error. This dictionary is personal to your user account on that computer — if someone else logs into the same computer with a different account, they will not see your added words.

If you switch to a different computer or a different version of Word, your personal dictionary does not follow you. You would need to add those words again. If you use Word Online and Word on your desktop, they have separate dictionaries, so you may need to add the same words to both.

How to turn off the red squiggles (and why you might not want to)

If the red squiggles bother you while you are drafting, you can turn them off temporarily. On Windows, go to File, then Options, then Proofing, then uncheck "Check spelling as you type." On Mac, go to Word, then Preferences, then Spelling, then uncheck "Check spelling as you type." The squiggles disappear, but spell check still runs when you use the Review tab or Editor button.

Most people find it easier to just ignore the squiggles while drafting and run a full check when the document is finished. Turning off automatic checking means you might miss errors if you forget to run the full check later. A better approach is to ignore individual words you know are correct (using "Ignore All") rather than turning off the whole system.

What spell check catches and what it misses

Spell check catches misspelled words and, in newer versions, some grammar problems. It does not catch words that are spelled correctly but used in the wrong context — like writing "their" instead of "there," or "its" instead of "it's." It also does not catch missing words, repeated words, or awkward phrasing that is technically correct but sounds wrong.

This is why grammar check exists alongside spell check. If you are writing something important — a cover letter, a formal email, a document for work — run both spell check and grammar check, then read through the document yourself. No tool catches everything, and a human reader will spot things no software can.

Frequently Asked Questions

Why does Word mark a word as wrong when I know it is spelled correctly?

Word uses a built-in dictionary, and that dictionary does not include every word in the English language. Proper names, technical terms, brand names, and words from other languages often get marked as errors even though they are correct. Right-click and choose "Add to Dictionary" to teach Word that word is correct, and it will stop marking it as an error.

Can I undo adding a word to my dictionary?

Yes, but the process is different on Windows and Mac. On Windows, go to File, Options, Proofing, then click "Custom Dictionaries" and find the dictionary file, then edit it to remove the word. On Mac, the custom dictionary is stored in a hidden folder and is harder to access. The easiest fix is to just ignore that word using "Ignore All" instead of adding it.

Does spell check work the same way in Word Online as it does in Word on my computer?

Mostly yes, but Word Online is simpler. It does not have all the same options, and it uses the Editor button instead of a separate Spelling button. Your personal dictionary in Word Online is separate from the one on your desktop, so you may need to add words to both. Word Online spell check works in any web browser.

What if I want spell check to ignore a whole category of words, like all words in a different language?

Word does not have a built-in way to ignore entire categories. Your best option is to add those words to your dictionary one at a time as they come up, or to use "Ignore All" each time you encounter them. If you write in multiple languages regularly, you might consider using a specialized tool designed for that purpose.

Does turning off spell check affect grammar check?

No. Turning off "Check spelling as you type" only stops the red squiggles from appearing while you work. Grammar check (the green squiggles in newer versions) runs separately and can be turned on or off independently. You can also run the full Editor or Spelling pane even if you have turned off automatic checking.