Signup vs. Sign-up vs. Sign Up
“Sign up” is the two-word phrasal verb for enrolling or registering. “Sign-up” is a documented noun for the act or instance of registering, and Dictionary.com also records the closed noun spelling “signup.”
Use “sign up” for the verb. For the noun, “sign-up” is widely documented and “signup” is also recorded as an alternative spelling.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| the action of enrolling or registering | sign up | Use the two-word phrasal verb. |
| the noun naming registration or an instance/process of it | sign-up | Use the widely documented hyphenated noun. |
| an alternative closed noun spelling | signup | The closed noun is also recorded; follow the relevant style consistently. |
Quick tests
Meaning / construction test
Is the expression functioning as the verb meaning enroll/register?
If yes: Use “sign up.”
If no: For the noun, “sign-up” is widely documented and “signup” is also recorded as an alternative.
Caveat: The reviewed sources document more than one noun spelling; the verb remains two words.
Examples
You can sign up online.
The expression is the phrasal verb.
The sign-up closes on Friday.
The hyphenated form is the noun.
The signup page asks for an email address.
The closed noun spelling is also documented.
Further guidance
Core difference
Use “sign up” when the expression functions as a verb; use the documented noun form for the person, thing, event, result, or modifier.
Fast Test
If tense or inflection works naturally—such as a past or -ing form—you are using the verb and should keep “sign up” as separate words.
Variant Boundary
Cambridge documents “sign-up” as a noun and “sign up” as a verb; Dictionary.com also records closed “signup” as an alternative noun spelling.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- SIGN UP — English meaning (opens in a new tab)Cambridge Dictionary · Two-word phrasal verb “sign up” and hyphenated noun “sign-up” in Business English
- SIGN-UP Definition & Meaning (opens in a new tab)Dictionary.com · Noun “sign-up,” with “signup” documented as an alternative spelling