warm up (warm-up)

Quick answer

Keep the verb open (warm up, set up, check in). Hyphenate or close the form when the phrase is a noun or a compound modifier before a noun (a warm-up, the setup, a check-in time). If an article like "a" or "the" fits naturally before the phrase, treat it as a noun/modifier.

Core explanation

Decide by grammatical function: noun/modifier = hyphen or closed form; verb = separate words. Use two quick tests: the article test (a/the) and the tense test (-ed/-ing) to check function instantly.

Hyphenation rules

Compound modifier before a noun → hyphenate: a well-timed warm-up.
Nominalized phrasal verbs often become closed or hyphenated: backup, setup, check-in.
When a phrase names a thing, switch to noun rules: the setup, a pick-me-up.
Check a current dictionary for settled closed forms (makeup vs make-up).

Spacing and phrasal verbs

Phrasal verbs stay as two words when they act as verbs and accept tense changes: they warmed up, please back up the files, she handed in the form. Do not hyphenate these verb uses.

Verb use → open: warm up, set up, check in, back up, hand in.
Noun/modifier use → hyphen or closed: a warm-up, the setup, a check-in.
Adverbs and tense markers confirm verb use: they immediately set up the conference.

Memory tricks

Fast checks to decide without a dictionary:

Article test: if "a/the" fits naturally → noun/modifier → hyphen/closed (a warm-up).
Tense test: if you can add -ed/-ing to the verb and it still makes sense → verb → open (they warmed up).
Position test: if the phrase sits directly before another noun to describe it → hyphenate (a warm-up routine).

Rewrite help: templates and ready rewrites

If you're unsure, apply the tests or rephrase for clarity. These templates fix most errors quickly.

Noun template: use "a/the" + compound → hyphen or closed (a setup, the check-in).
Verb template: subject + verb + particle + object → keep open (They set up the system).
Safe fallback: convert the noun into a verb: "They warmed up" instead of "they did a warm-up."

Wrong: We did a set up. →
Correct: We completed the setup. / We set up the projector.
Wrong: Please backup the files. →
Correct: Please back up the files.
Wrong: That talk was a real pick me up. →
Correct: That talk was a real pick-me-up.
Wrong: She will hand-in the essay. →
Correct: She will hand in the essay. / Her hand-in is Friday.
Wrong: They did a backup before updating. → Better: They backed up their data before updating.
Wrong: Please check-in at reception when you arrive. →
Correct: Please check in at reception when you arrive. (Unless you mean "a check-in time")

Examples: wrong → right (work, school, casual)

Work: files, meetings, equipment. School: sports, assignments, labs. Casual: messages, feelings, outings.

Work - Wrong: Please backup your files before the update. →
Right: Please back up your files before the update.
Work - Wrong: We need a set up for the projector before the meeting. →
Right: We need a setup for the projector before the meeting.
Work - Wrong: Please check-in at reception when you arrive. →
Right: Please check in at reception when you arrive.
School - Wrong: The students did a warm up before lab. →
Right: The students did a warm-up before lab. / They warmed up before lab.
School - Wrong: She will hand-in the assignment on Friday. →
Right: She will hand in the assignment on Friday.
School - Wrong: He warmed-up for five minutes and then played. →
Right: He warmed up for five minutes and then played.
Casual - Wrong: That hike was a real pick me up after exams. →
Right: That hike was a real pick-me-up after exams.
Casual - Wrong: She bought a make up kit and then made up an excuse. →
Right: She bought a makeup kit and then made up an excuse.
Casual - Wrong: He will pick up the parcel - it's a real pick me up. →
Right: He will pick up the parcel - it's a real pick-me-up.

Similar mistakes to watch for

Many errors follow the same verb vs noun/modifier logic or reflect historical changes in spelling. When a form has gone from open → hyphenated → closed, check a current dictionary and stay consistent across a document.

back up (verb) vs backup (noun/adjective)
set up (verb) vs setup (noun)
check in (verb) vs check-in (noun/modifier)
follow up (verb) vs follow-up / followup (noun - style varies)
make up (verb) vs makeup (noun/adjective)
pick up (verb) vs pick-me-up (noun)

Work - Wrong: Make a follow up with the client. →
Right: Make a follow-up with the client. / Follow up with the client.
Work - Wrong: Create a back up of the database. →
Right: Create a backup of the database.

FAQ

Should I write "warm up" or "warm-up"?

Use "warm up" for the verb (they will warm up). Use "warm-up" for the noun or a compound modifier before a noun (a warm-up, warm-up routine). If "a warm-up" sounds correct, hyphenate or close the form.

Is "setup" one word or two?

"Setup" is usually one word when it's a noun (the setup). Use two words for the verb: set up (we will set up the account). Confirm with your dictionary or style guide if unsure.

Can I hyphenate phrasal verbs in emails?

Only if they're acting as a noun or modifier (a check-in time). For verb uses, keep the words separate. In informal messages, clarity and consistency matter more than pedantic hyphen rules.

Why do some compounds close over time but others stay hyphenated?

Language evolves: frequent, lexicalized compounds often close (backup, email). Less frequent or multiword expressions often remain hyphenated. When in doubt, consult a current dictionary.

Quick edit: "The players did a warm up" - is that wrong?

Yes. In that sentence "warm up" is a noun, so write "The players did a warm-up." Or rewrite it as the verb: "The players warmed up." Choose the form that best fits tone and clarity.

Want a fast check on your sentence?

Run a quick article/tense test: try "a/the" before the phrase and try adding -ed/-ing to the first word. If the tests point to a noun/modifier, hyphenate or close the form; if they point to a verb, keep it open. For teams, save a short style list (setup, back up/back-up, check in/check-in) to avoid repeated edits.