How to Correctly Use Checkup vs Check-Up in Writing

A clear choice between checkup and check-up matters when you write.

This article explains what both forms mean, how people use them, and which form is more common in different places. Nouns: checkup functions mainly as a compound noun meaning a medical or routine review.

Verbs: when writers use check up as a verb phrase, it separates into two words and changes meaning. Adjectives: modifiers like annual or routine describe the kind of checkup. Adverbs: words such as regularly or quickly tell how the action happens. Prepositions: common pairings are for a checkup, after a checkup, and during a checkup. Conjunctions and pronouns: simple connectors (and, or, but) and pronouns (it, they) link ideas about checkups smoothly.

Table of Contents

Parts of speech analysis

Nouns: “checkup” as a compound noun

checkup is usually a noun meaning an examination or review (e.g., “I had a checkup”). In that sentence, I is the pronoun (subject), had is the verb (past tense), and a is the article (determiner).

Verbs: “check up” as a verb phrase

When you mean to perform the action, use the verb phrase check up on or check up. Example: “They check up on the patient.” Here they is the subject (pronoun), check up is the verb (present simple), and on is a preposition.

Adjectives: words that describe checkups

Adjectives like annual, routine, full, quick modify checkup (e.g., “an annual checkup”). They answer which one or what kind.

Adverbs: how actions are done

Adverbs such as regularly, quickly, thoroughly modify verbs or even adjectives (e.g., “She checks up regularly” — regularly modifies the verb).

Prepositions: linkers with checkup

Common prepositions are for, after, during, before, on (e.g., “for a checkup”, “after the checkup”). They connect the noun to time, purpose, or place.

Conjunctions: joining ideas smoothly

Conjunctions like and, but, or, because join clauses (e.g., “I need a checkup, but I am busy”). Watch commas around conjunctions to avoid run-ons.

Pronouns: replace nouns in sentences

Pronouns such as it, they, we can replace checkup or people (e.g., “I scheduled it for Friday” — it = the checkup). Make sure pronouns clearly match their nouns.

What “checkup” and “check-up” mean

A checkup (one word) is most often a noun. It usually means a medical examination or a routine review of something. For example: “She booked a checkup with her doctor.” That sentence is correct: she (pronoun) is the subject, booked (verb, past) shows action, and a is the article.

Check-up with a hyphen is also used, especially in some style guides or older writing. Hyphenation sometimes happens when a compound word is new or when authors want to emphasize the two parts. Over time, many compounds lose their hyphen and become one word.

When the phrase is a verb, writers separate the words: check up (two words) or check up on. For example: “Please check up on the equipment.” Here check up is a phrasal verb and on is a preposition that completes the verb meaning.

Parts of speech check (example):

Please (adverb making the sentence polite), check up (verb), on (preposition), the equipment (noun phrase: the article + equipment noun).

Historical and style notes (short)

Many English words started as two words, became hyphenated, and then joined as one word. Checkup followed this path in everyday use. Different dictionaries and style guides may show both checkup and check-up, but the one-word form is now common in modern American English. British English may accept both but often favors the single word in medical contexts.

Key points: when to use each form

Use checkup (one word) when writing a noun: “I have a dental checkup.”
- Grammar check: I (subject pronoun) + have (present) + a (article) + dental (adjective) + checkup (noun).
Use check up (two words) as a verb or phrasal verb: “They check up on the patient every week.”
- Grammar check: they (pronoun subject) + check up (verb present) + on (preposition) + the patient (noun phrase).
Check-up (hyphen) is optional in some style guides but is less common now; when in doubt, prefer checkup for the noun.

Contextual examples and parts-of-speech notes

Medical context (simple)

Sentence: “He went for a checkup.”
- Nouns: he, checkup; Verb: went (past); Preposition: for; Article: a.
- Note: Sentence is short, correct tense, clear subject-verb agreement.

Workplace or machine check

Sentence: “We scheduled a system checkup to test software.”
- Nouns: we, system, checkup, software; Verb: scheduled (past); Adjective: system modifies checkup.

Using “check up” as verb

Sentence: “Please check up on the patient tonight.”
- Please (polite adverb), check up on (phrasal verb), the patient (object), tonight (adverb of time).

Hyphen example (less common)

Sentence: “The doctor recommended a check-up next month.”
- Grammar: This is acceptable but modern usage favors checkup.

Common mistakes and how to fix them

**Using checkup as a verb**

Wrong: “I will checkup on him.” Fix: “I will check up on him.”

Explanation: checkup is a noun; for the verb use two words. Check verbs for correct form and subject-verb agreement (e.g., I will check up, she checks up).

Mixing hyphen and one-word form inconsistently

Wrong: “After the check-up, she booked another checkup.” Fix: Choose one style and be consistent: “After the checkup, she booked another checkup.”

Explanation: Consistency in hyphenation makes writing cleaner.

Run-on sentences with conjunctions

Wrong: “I need a checkup I don’t have time.” (run-on) Fix: “I need a checkup, but I don’t have time.” or “I need a checkup. I don’t have time.”

Explanation: Use commas with coordinating conjunctions (and, but, or) to avoid run-ons.

Missing articles

Wrong: “I had checkup yesterday.” Fix: “I had a checkup yesterday.”

Explanation: Many countable nouns need articles (a, an, the). Check checkup as a countable noun: one checkup, two checkups.

American vs British English differences

American English: prefers checkup as the noun in medical contexts. Example: “annual checkup.”
British English: also accepts checkup, though older or formal texts may show check-up. Both are understood.
Verb usage: both varieties use check up (two words) for the verb form.
Tip: Follow a single style guide (e.g., Oxford, Cambridge, Chicago) for consistent hyphenation in a document.

Idiomatic expressions and related phrases

Check up on — to examine or monitor someone or something. Example: “Can you check up on the kids?”
- Grammar: Can (modal verb), you (subject pronoun), check up on (verb phrase), the kids (object).
Give a checkup — to perform an examination. Example: “The mechanic gave the car a quick checkup.”
Get a checkup — to receive an exam. Example: “I get a checkup every year.”
- Notice the verb forms: “give” (base), “get” (present simple) — match subject-verb agreement.

Practical tips for writers (simple and clear)

When using the word as a noun, write checkup (one word).
When using it as a verb, write check up (two words) and add on if needed: check up on.
Avoid mixing check-up and checkup in the same piece. Pick one.
Use articles correctly: a checkup, the checkup, an annual checkup.
Keep sentences short and active when possible: “She scheduled a checkup” is better than a long passive chain.
If you follow a style guide at work or school, use that guide’s preference. If not, default to the single word noun checkup.
Proofread for run-ons and fragments; read sentences aloud to catch errors.

Sentence structure checks and edits (examples)

Original: long and messy

“Because I was busy I had to postpone my checkup and the doctor called and then I rescheduled it for next month.” (This is long and close to a run-on.)

Edited (clear)

“I was busy, so I postponed my checkup. The doctor called, and I rescheduled it for next month.”
- Analysis: Sentences split to avoid run-on. Conjunction so correctly connects cause and effect. Subject-verb agreement maintained.

Original: fragment

“After the checkup.” (Fragment — incomplete thought.)

Edited (complete)

“After the checkup, she felt better.”
- Analysis: Fragment becomes a complete sentence by adding subject and verb.

Practical checklist for proofreading “checkup” uses

Is the term used as a noun? If yes → use checkup.
Is the term used as a verb? If yes → use check up (and consider adding on).
Is an article needed? (a, an, the) Add if noun is countable.
Are sentences short enough? Break long ones.
Are conjunctions used correctly with commas? Use comma + conjunction or split sentences.
Are pronouns clear and matched to their nouns? Replace ambiguous pronouns with the noun if needed.

Rewriting for improved clarity, grammar, and style

I revised the article for clear grammar, consistent word choice, and simple wording. Main changes made:

Standardized the noun form to checkup throughout the article.
Used check up (two words) consistently for verb uses.
Shortened long sentences and fixed run-ons by adding commas or splitting sentences.
Checked all verbs for correct tense and subject-verb agreement (examples used present simple, past simple, and modals appropriately).
Added articles where needed: a checkup, the checkup.
Simplified complex phrases and avoided awkward modifiers.

Revised example paragraph (simple)

Original: “Because I had little time I had to postpone my checkup and then the doctor called me to reschedule the check-up which made me rearrange my plans.” Rewritten: “I had little time, so I postponed my checkup. The doctor called to reschedule, and I changed my plans.”

Notes: Clear subject-verb structure, consistent noun form, split into short sentences.

Conclusion

Checkup vs check-up is mainly a question of hyphenation history and style. Use checkup as a noun for a medical or routine examination, and use check up as a verb phrase when describing the action. Avoid run-on sentences, use articles with countable nouns, and keep pronouns clear. For most writing today, the single word checkup is a safe and modern choice. Picking one style and staying consistent helps readability and makes your writing look professional.

FAQs

Q: Is checkup one word or two words? A: As a noun, it is usually one word: checkup. As a verb, use two words: check up.
Q: Can I write check-up with a hyphen? A: Yes, some guides allow check-up, but modern usage prefers checkup. Be consistent.
Q: Which is correct: “get a checkup” or “get a check-up”? A: Both are understood. Prefer get a checkup for modern, simple style.
Q: How do I use the verb form? A: Use check up or check up on: e.g., “I will check up on the project.”
Q: Do I need an article before checkup? A: Most times yes: a checkup, the checkup, an annual checkup.
Q: Is there a difference in American and British English? A: Small. Both accept checkup, though British texts sometimes keep check-up. Use one form consistently.
Q: Is checkup countable? A: Yes. You can say one checkup, two checkups.
Q: Can checkup be used for machines? A: Yes. You can say a system checkup or a quick checkup on the engine.
Q: How do I avoid run-on sentences with checkup phrases? A: Use commas with conjunctions or split long ideas into short sentences.
Q: Where should I look for the final style rule? A: Follow your required style guide (school, publisher, or workplace). If none, use checkup for the noun and check up for the verb.