The correct spelling is "spell check" — two words, lowercase
When you write about the feature, use spell check (two words) or spell-check (hyphenated when it modifies a noun, like "spell-check tool"). The word "spell" comes first because you are checking spelling. Most style guides treat it as a compound noun rather than a single word.
You will see it written different ways across the internet, but two words is the standard in published writing and technical documentation. If you are writing for school or work and a style guide is specified, check that first — some organizations have their own rules. When in doubt, two words is always correct.
Key Takeaways
- The correct spelling is "spell check" (two words) or "spell-check" (hyphenated when describing a noun).
- Never write it as one word ("spellcheck"), though some software companies use that in product names.
- Capitalize it only if it is part of an official product name, like "Microsoft Word's Spell Check feature."
- The hyphenated version ("spell-check") is correct when the term modifies another word, such as "spell-check software."
When to use the hyphenated version
Use a hyphen when "spell check" comes before a noun and modifies it. For example: "The spell-check feature caught my typo" or "I enabled spell-check mode." The hyphen connects the two words so they function as a single descriptor.
Without the hyphen, write it as two separate words: "I turned on spell check" or "The spell check found an error." This is the most common way you will see it in sentences where it stands alone or comes after a verb.
Why companies sometimes write it differently
Software companies often trademark their own versions with different spellings. Microsoft Word calls it "Spell Check" (capitalized, two words). Grammarly uses "spell check" in lowercase. Some older software or specialized tools may write it as one word in their branding, but that does not change the correct spelling in regular writing.
When you are referring to the feature generically — not as a product name — use the standard two-word spelling. When you are naming a specific tool or feature as it appears in software, match what the company uses. This distinction matters most when you are writing documentation or instructions that other people will read.
Common misspellings to avoid
The most frequent mistakes are writing it as one word ("spellcheck") or capitalizing it in the middle of a sentence when it is not a product name. Both are incorrect in formal writing. You might also see "spell-checker" (the tool that does the checking) or "spell-checking" (the action), but the feature itself is "spell check."
If you are unsure which version to use, remember: two words, lowercase, unless it is part of a product name or comes before a noun (then add the hyphen). This covers nearly every situation you will encounter in your own writing.
How spell check actually works
Spell check compares the words you type against a dictionary database. When it finds a word that does not match anything in that dictionary, it flags it as a potential error. It does not understand context or meaning — it only knows whether a word exists in its list.
This is why spell check misses real errors. If you type "their" when you meant "there," spell check sees a real word and moves on. It also flags correctly spelled words that are straightforward not in its dictionary, like proper names or technical terms. That is why you can add words to your dictionary so the tool stops marking them as wrong.
Spell check versus grammar check
Spell check and grammar check are different tools, though they often run together. Spell check finds misspelled words. Grammar check looks for sentence structure problems, punctuation errors, and word choice issues. A word can be spelled correctly but used incorrectly — grammar check is what catches that.
Most modern writing software includes both. Microsoft Word has a "Spell Check" feature and a separate grammar-checking system. Grammarly combines them into one interface. Understanding the difference helps you know which tool to turn to when you need help with different kinds of writing problems. Many writers rely on both running simultaneously to catch the widest range of mistakes.
When spell check fails and what to do instead
Spell check cannot catch homophones (words that sound the same but have different meanings), words used in the wrong context, or typos that accidentally form real words. If you type "form" instead of "from," spell check will not flag it because both are legitimate words. This is where reading your work aloud or having someone else review it becomes essential.
For important documents, combine spell check with manual proofreading. Read slowly, check words you are uncertain about in a dictionary, and pay special attention to commonly confused pairs like "accept" and "except" or "affect" and "effect." Spell check is a helpful first pass, but it is not a complete solution.
Frequently Asked Questions
Is "spellcheck" ever correct?
Not in standard English writing. Some software companies use "spellcheck" as a brand name or in their code, but the correct spelling in sentences is "spell check" (two words) or "spell-check" (hyphenated before a noun). Stick with two words unless you are quoting a product name.
Do I capitalize spell check in the middle of a sentence?
No, unless it is part of a product name. Write "I ran spell check on my document" in lowercase. Capitalize it only when referring to a specific feature by its official name, like "Microsoft Word's Spell Check feature."
What is the difference between spell check and spell checker?
Spell check is the feature or action (the thing you do). Spell checker is the tool that performs it (the software component). You might say "I used the spell checker" or "I ran spell check." Both are correct, but they refer to slightly different things.
Should I hyphenate spell check when it comes after a verb?
No. Use the hyphen only when "spell check" comes before and modifies a noun. After a verb, write it as two words: "I turned on spell check" not "I turned on spell-check." The hyphen is only needed when the term acts as a descriptor.
Can spell check catch my grammar mistakes?
No. Spell check only finds misspelled words. Grammar check is the separate tool that catches sentence structure, punctuation, and word choice problems. You need both tools running to catch the full range of writing errors.