Login is a noun, log in is a verb

Login (one word) is a noun. It refers to the act of signing in, or the credentials you use to sign in — your username and password together. You might say "I forgot my login" or "Enter your login information."

Log in (two words) is a verb phrase. It describes the action of signing into an account. You would say "I need to log in to my email" or "She logged in this morning."

The confusion exists because the words sound identical when spoken and the distinction matters only in writing. Most people use them interchangeably in casual conversation, but the one-word and two-word versions serve different grammatical purposes.

Key Takeaways

  • Use "login" (one word) when referring to a noun — the account credentials or the sign-in screen itself.
  • Use "log in" (two words) when describing the action of signing into an account.
  • The same rule applies to related forms: "log out" (verb) versus "logout" (noun).
  • Tech companies often use "login" on buttons and screens because it functions as a label, even though "log in" is technically more correct for the action.

How to tell the difference in a sentence

A simple test: replace the word with a different verb. If you can substitute "sign in" or "enter," you need the two-word version. If you cannot, use one word.

"I need to log in to my account" works because you can say "I need to sign in to my account." The verb form is correct.

"My login is not working" works because "login" is the noun — the thing itself, not the action. You cannot say "My sign in is not working" in the same way.

Another way to check: if a word like "my," "the," or "your" comes before it, you probably need the noun form. "My login credentials" (noun). "I need to log in" (verb, no possessive).

Why tech companies blur the line

Most websites and apps use "Login" as the label on buttons, even though "Log In" would be grammatically stricter. This happens because button labels function as nouns — they name the action rather than describe it. A button that says "Log In" is technically correct, but "Login" has become the industry standard.

Email providers, social networks, and banking sites almost always label their sign-in buttons "Login" or "Sign In." This consistency has made the one-word version feel natural to users, even when the two-word version would be more precise in formal writing.

The same pattern holds for "logout." Most interfaces use "Logout" as a button label, though "log out" is the correct verb form in sentences.

Logout follows the same pattern

Logout (one word) is a noun referring to the sign-out process or the button that ends your session. "Click the logout button" or "I performed a logout."

Log out (two words) is a verb phrase describing the action of ending your session. "I need to log out before I leave" or "She logged out of her account."

The same test applies: if you can replace it with "sign out," use two words. If it is a thing or label, use one word.

What matters in different contexts

In formal writing — emails to your boss, documentation, published articles — the distinction between login and log in matters. Using the correct form shows attention to detail and follows standard grammar rules.

In casual communication — texts, chat messages, social media — most people do not notice or care which version you use. The meaning is clear either way.

In technical documentation and user interfaces, consistency matters more than correctness. If your company's style guide says to use "Login" on all buttons, follow that guide even if "Log In" would be more grammatically precise.

Common mistakes and how to avoid them

The most frequent error is using "login" as a verb: "Login to your account" should be "Log in to your account." This happens because the noun form has become so common in interface design that people default to it.

Another mistake is using "log in" as a noun: "I forgot my log in" should be "I forgot my login." This is less common but still appears in casual writing.

The easiest way to catch these errors is to read the sentence aloud and ask yourself: am I describing an action, or am I naming a thing? Actions use two words. Things use one.

Frequently Asked Questions

Is it wrong to use login as a verb?

Grammatically, yes — the correct verb form is "log in" (two words). However, "login" as a verb has become so common in casual speech and writing that many people do not notice the error. In formal writing, use "log in." In everyday conversation, either form is understood.

Why do websites use Login on buttons instead of Log In?

Button labels function as nouns or commands rather than full sentences, so "Login" has become the standard label. It is shorter, fits better on small screens, and has become the expected convention. This does not make it grammatically correct in a sentence, but it is the industry norm.

Does this rule apply to other tech terms?

Yes. The same pattern holds for "log out" (verb) versus "logout" (noun), "sign in" (verb) versus "sign-in" (noun), and similar paired terms. If the word describes an action, use two words or a hyphen. If it names a thing, use one word.

Should I correct someone who uses login as a verb?

In casual conversation, no. The meaning is clear and correcting someone is usually not helpful. In formal writing you are editing or in professional documentation, yes — use the correct form. Context and relationship matter more than grammar pedantry.