sign up (sign-up)

Writers stumble over sign up / sign-up / signup because English treats actions, modifiers, and nouns differently. Below are short rules, quick tests you can apply in seconds, plenty of copy-paste fixes for work, school, and casual situations, and simple rewrites you can drop into your text.

Quick answer

Use sign up (two words) for the verb, sign-up (hyphen) when the phrase directly modifies a noun, and sign-up or signup for the noun depending on style and format.

Verb (action): sign up - I will sign up tonight.
Compound adjective (before a noun): sign-up - the sign-up sheet.
Noun (the thing/process): sign-up or signup - a sign-up; new user signups.

Core explanation (short)

Decide the phrase's role: action, modifier, or name. Quick test: can you change tense? If yes, it's a verb (two words). Is it directly before a noun and answering "what kind of X"? Hyphenate. Is it a named item you can count or pluralize? Treat it as a noun and pick sign-up or signup per style.

Action → two words (sign up).
Before a noun → hyphenate (sign-up + noun).
Noun → sign-up or signup; be consistent.

Hyphenation vs spacing: clear steps and quick tests

Apply these checks in order:

Verb test - change tense: signed up / signing up → use two words.
Modifier test - place before the noun: sign-up form → hyphenate.
Noun test - add article or pluralize: a sign-up / sign-ups → noun form (hyphen or closed).

Wrong: Please sign-up by Friday.
Right: Please sign up by Friday.
Wrong: We'll review the signup forms tomorrow.
Right: We'll review the sign-up forms tomorrow.

Compound adjectives: when to hyphenate before a noun

Hyphens show words work together to modify a noun. Use sign-up when the pair sits directly before a noun: sign-up sheet, sign-up deadline, sign-up link. After the noun, don't hyphenate: the deadline to sign up; we will sign up.

Before noun → hyphen: sign-up deadline.
After noun or verb → no hyphen: the deadline to sign up; we signed up.

Work wrong: Submit your sign up sheet to HR. Work right: Submit your sign-up sheet to HR.
School wrong: Turn in your signup form to the office. School right: Turn in your sign-up form to the office.
Casual wrong: Who's in charge of the sign up page? Casual right: Who's in charge of the signup page?

Noun vs verb: grammar checks with examples

Verbs change tense and take objects: I will sign up; she signed up for the course. Nouns take articles and pluralize: the sign-up; sign-ups. If you can add "the" or make it plural naturally, treat it as a noun.

Verb → change tense: sign up → signed up.
Noun → add article/plural: a sign-up; sign-ups.
Modifier → place before noun and hyphenate: sign-up meeting.

Wrong: I completed the signup for the event.
Right: I completed the sign-up for the event.
Verb wrong: We will signup tomorrow. Verb right: We will sign up tomorrow.
Usage: We recorded 300 sign-ups this week (acceptable in reports).

Real usage and tone: match form to audience and format

Choose forms to match your audience and medium. Formal writing tends to prefer sign up (verb) and sign-up (noun/adjective). UI labels, dashboards, and product copy often use signup for brevity. In chat and email, favor clarity: sign up for actions, sign-up when modifying a noun.

Formal/print: sign up (verb) and sign-up (noun/adjective).
Web/UI/product: signup is common for labels and metrics.
Casual/chat: be consistent; use sign up for actions and signup for short links/buttons.

Work memo: Please sign up for office safety training by Friday.
Dashboard: Metric label: New signups.
Student notice: Sign-up opens Monday.
Group chat: They posted a signup link in the chat.

Try your own sentence

Test the whole sentence rather than the phrase alone; context usually makes the right form obvious.

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

Pick the context that matches your sentence and copy the "right" line to fix it instantly.

Work wrong: Please signup for the training by Friday. Work right: Please sign up for the training by Friday.
Work wrong: Attach the sign up sheet to your report. Work right: Attach the sign-up sheet to your report.
Work usage: New user signups (dashboard label).
School wrong: Students need to sign-up for electives next week. School right: Students need to sign up for electives next week.
School wrong: The signup deadline has passed. School right: The sign-up deadline has passed.
Casual wrong: I'll sign-up later. Casual right: I'll sign up later.
Casual wrong: Post the sign up link here. Casual right: Post the signup link here.

Rewrite help: three quick edits + ready rewrites

Checklist (3 steps): 1) Identify role: verb/adjective/noun. 2) Apply form: sign up / sign-up / signup. 3) If it still feels awkward, rewrite with a different verb (register, enroll) or restructure the sentence.

Ready rewrites you can copy and edit for tone:

Rewrite work email: Original: Please complete sign up
Rewrite: Please sign up via the attached form by Friday.
Rewrite memo: Original: Sign-up begins Monday; signup ends Friday.
Rewrite: Registration opens Monday and closes Friday.
Rewrite syllabus: Original: The sign up sheet is at the front desk.
Rewrite: The sign-up sheet is at the front desk.
Rewrite UI button: Original button: Sign Up Now Rewrite (short): Signup
Rewrite casual chat: Original: I'll sign-up later.
Rewrite: I'll sign up later.

Memory tricks and quick cheats

Two fast cues keep edits consistent: "Action = two words" and "Before noun = hyphen." If you're unsure, substitute a different verb like register or enroll to avoid the hyphen decision.

"Action = two words" → I will sign up.
"Before noun = hyphen" → sign-up sheet.
UI labels: think "short and solid" → signup for buttons and metrics.

Similar mistakes and other hyphenation traps

The same tests apply to pairs like log in / log-in / login, follow up / follow-up / followup, check in / check-in / checkin. Also, don't hyphenate adverb + adjective compounds when the adverb ends in -ly (highly paid, not highly-paid).

Log in (verb) / log-in (modifier) / login (noun/UI).
Follow up (verb) / follow-up (noun) / followup (rare).
Check in (verb) / check-in (noun/modifier) / checkin (UI).

Usage: Wrong: Please login to the portal.
Right: Please log in to the portal. UI label: Login
Usage: Wrong: We will follow-up.
Right: We will follow up. Noun: a follow-up meeting.
Usage: Wrong: I need to checkin.
Right: I need to check in. Noun/UI: check-in or checkin.

FAQ

Is it "sign up" or "sign-up"?

Use sign up (two words) for the verb. Use sign-up (hyphen) when the phrase modifies a noun. For the noun, some style guides accept signup; choose the form that fits your audience and stay consistent.

Can I write signup as one word?

Yes-signup is common in web and product contexts for labels and metrics. In formal prose, many editors prefer sign-up or sign up, so match your style guide.

Do I always hyphenate before a noun?

When two or more words act together immediately before a noun as one modifier, hyphenate. If the phrase comes after the noun or is a verb, don't hyphenate.

Should I change all sign-up / signup instances in a document?

Make forms consistent across a document. Pick the convention that fits your audience (formal vs UI) and apply it everywhere or follow the publication's style guide.

What if it's still unclear which form to use?

Remove ambiguity by rewriting: use a different verb (register, enroll) or restructure the sentence (Please sign up via this form; The sign-up sheet is on the desk). Clarity beats pedantry.

Need a quick sentence check?

Paste a sentence into your editor and run the tests: action = sign up; before a noun = sign-up; UI label/metric = signup. Or copy one of the rewrites above and adjust tone as needed.