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
| If you mean / need | Use | Why |
|---|---|---|
| the act or instance of registering | sign-up / signup | The hyphenated noun is standardly documented, and closed “signup” is also recorded as an alternative spelling. |
| the action of enrolling or registering | sign up | The phrasal verb is written as two words. |
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