Login vs Log In (and Log On, Sign In)
Log in (two words) is a verb: Log in to your account. Login (one word) is a noun or adjective: Enter your login, the login page. The same split applies to log on / logon, sign in / sign-in and log out / logout.
It's one of the most frequently broken rules in English, partly because so many apps and websites get it wrong on their own buttons. Once you see the pattern, though, you'll spot errors everywhere, and you'll keep them out of your own emails, help documents and résumés.
Quick answer: Use log in when it's something you do (I can't log in, She logged in at 9). Use login when it's a thing or describes a thing (my login doesn't work, login details). If you can put a tense ending on log (logged, logging), you need two words.
On this page
- The Verb: Log In
- The Noun and Adjective: Login
- Where "Log In" Comes From
- Log In, Log On, Sign In: What's the Difference?
- Log In To vs Log Into
- Examples in Context
- Writing Clear Interface and Help Text
- US vs UK vs Australia
- Common mistakes
- Edge Cases You'll Run Into
- A memory trick
- Practice quiz
- Getting It Right Every Time
The Verb: Log In
Log in is a phrasal verb. You log in when you identify yourself to a computer system. It's pronounced log IN, with the stress on in, and it behaves like any other verb:
- I log in every morning.
- She logs in from home on Fridays.
- We logged in after the update.
- He's logging in now.
- Have you logged in yet?
Notice the doubled g in logged and logging. That's standard spelling for short verbs ending in one vowel plus one consonant (jog, jogged; plan, planned).
Its opposites follow the same pattern: log out and log off are verbs, while logout is a noun or adjective (the logout button).
The Noun and Adjective: Login
Login is a compound noun made from the verb, pronounced LOG-in, stress on the first syllable. That stress shift from verb to noun is common in English compounds and is a handy check if you read your writing aloud.
As a noun, login can mean:
- The credentials themselves: Can you send me your login? (meaning username and password)
- The act or instance of logging in: The system recorded three failed logins.
- The screen or process: The login is slow today.
As an adjective (a noun modifying another noun), it describes something connected with logging in: login page, login screen, login credentials, login attempts, login issues.
Where "Log In" Comes From
The phrase draws on the older nautical sense of log. Ships kept a log, a record of speed, position and events, named after the wooden log once thrown overboard on a line to measure speed. To log something came to mean to enter it in a record.
When multi-user computers arrived in the mid-twentieth century, users had to identify themselves so that their usage could be recorded. Logging in (or logging on) was, quite literally, entering yourself in the system's log. The noun forms login and logon followed soon after, as computing jargon tends to compress phrasal verbs into nouns quickly.
Sign in has an older, non-digital history. People signed in at hotels, offices and visitor books long before computers existed, by writing their names. Its move into software was a natural extension.
Log In, Log On, Sign In: What's the Difference?
In modern usage, these all mean essentially the same thing. The differences are about tone and tradition rather than meaning.
| Term | Verb form | Noun/adjective form | Tone and typical use |
|---|---|---|---|
| Log in | log in | login | Standard, slightly technical; very common |
| Log on | log on | logon | Older; associated with networks and older systems |
| Sign in | sign in | sign-in | Friendly, plain English; favored by many consumer apps |
| Sign on | sign on | sign-on | Mainly in single sign-on (SSO); otherwise means joining or enlisting |
| Log out / off | log out, log off | logout, logoff | Opposites of log in / log on |
| Sign out | sign out | sign-out | Opposite of sign in |
A sensible rule for any document, website or app: pick one pair and stick to it. If your button says Sign in, the opposite should be Sign out, not Log out. Mixing them makes users wonder whether they're different actions.
Sign on is worth separating. In British and Australian English, signing on has historically meant registering for unemployment benefits, and in all three countries it can mean joining a team or crew (She signed on as first mate). In tech, it mostly survives in the fixed term single sign-on.
"Sign up" is different
Don't confuse any of these with sign up, which means creating a new account or registering for something. You sign up once; after that, you sign in or log in each time. The noun is sign-up (the sign-up form).
Log In To vs Log Into
This is where even careful writers disagree.
The traditional view says log in is the verb and to is a separate preposition, so you write log in to your account. This matches the logic of give in to and hand in to. Many style guides, including those used in edited publishing, still recommend it.
The descriptive view notes that log into has become extremely common, especially in American English and in technology, and that many dictionaries now record it. Some tech companies' own style guides accept or even prefer it.
What should you do?
- Formal, edited or international writing: log in to, sign in to.
- Casual writing or a house style that allows it: log into will not confuse anyone.
- Avoid login to entirely. That uses the noun as a verb and is wrong in every style.
The same reasoning, explained in more depth, appears in into vs in to and onto vs on to, which covers log on to.
Examples in Context
Everyday
- I can't log in to my bank app since I changed phones.
- Mum keeps writing her login on a sticky note on the fridge.
- Did you remember to log out of Netflix at your cousin's house?
- The login screen just keeps spinning.
- My daughter logged in to her school portal to check her marks.
- Every time I sign in, it asks me to verify my email again.
Workplace and email
- Please log in to the HR system and update your bank details by Friday.
- Your temporary login will expire after 24 hours.
- New starters in our Birmingham office receive their login credentials on day one.
- I've reset your password; you should be able to sign in now.
- We noticed several failed login attempts on your account from an unknown device.
- Remember to log off before leaving shared computers in the library.
- The client asked for a single sign-on option for their staff in Denver.
Technical and help documentation
- To log in, enter your email address and select Continue.
- The login page now supports two-factor authentication.
- Users who have not logged in for 90 days will be deactivated.
- Configure the logon script to map network drives automatically.
- Click Sign out in the top-right corner when you have finished.
News style
- Thousands of customers were unable to log in to online banking during the outage.
- Hackers obtained login details for more than a million accounts, the company said.
- Melbourne University students reported problems signing in to the exam platform.
- Officials urged residents of Texas to log on to the state website for updates on the storm.
Writing Clear Interface and Help Text
If you write buttons, emails or support pages, these conventions make your text easier to follow:
- Buttons are actions, so use the verb: Log in, Sign in, Log out. Capitalize only the first word in most modern interfaces.
- Field labels are things, so use the noun: Login email, Username.
- Link text should say what happens: Forgot your password? is clearer than Login help.
- Error messages should avoid blame: We couldn't sign you in. Check your email and password reads better than Invalid login.
US vs UK vs Australia
The core rule is identical across the three countries: two words for the verb, one word (or sometimes a hyphenated form) for the noun.
The differences are small:
- United States: Login as a closed noun is almost universal. Log into appears very frequently in American tech and business writing, though American style guides vary on accepting it. Sign in is widely used in consumer apps.
- United Kingdom: British publications more often hyphenate compound nouns, so log-in and sign-in (as nouns) appear alongside login. British editors are generally more likely to insist on log in to over log into. The phrase sign on also carries the separate meaning of registering for benefits.
- Australia: Australian usage mostly mirrors British conventions in edited writing, with log in to preferred and both login and log-in found as nouns. Australian government websites tend to favor plain-English choices such as sign in and log in. Signing on for unemployment support is also understood, though the official terminology has changed over time.
| US | UK | Australia | |
|---|---|---|---|
| Verb | log in | log in | log in |
| Noun | login | login or log-in | login or log-in |
| log into tolerance | high | lower in edited writing | moderate |
| Other meaning of sign on | join a team or crew | also register for benefits | also register for benefits (traditional) |
Common mistakes
❌ Please login to continue. ✅ Please log in to continue. After please, you need a verb.
❌ I forgot my log in. ✅ I forgot my login. After my, you need a noun.
❌ She loged in from the airport. ✅ She logged in from the airport.
❌ Your log in details are below. ✅ Your login details are below. Adjective before details.
❌ Click here to signin. ✅ Click here to sign in.
❌ Make sure you logout before leaving. ✅ Make sure you log out before leaving.
❌ Log in at the top, then click Log off. ✅ Log in at the top, then click Log out. Keep the paired terms consistent.
Edge Cases You'll Run Into
"Logged-in" before a noun. When the participle describes a noun, many style guides hyphenate it: logged-in users, a logged-in session. After the noun, drop the hyphen: Users who are logged in can see the dashboard. This follows the general rule for compound adjectives, and it applies equally to signed-in.
"Log in with." Interfaces often say Log in with Google or Sign in with your work account. That's the verb plus with, so it stays two words. The matching noun phrase is a Google login or social login.
"Logins" as a plural. Correct when you mean credentials or instances: We manage logins for 300 staff. Don't write log ins.
"Login" as a verb in casual chat. You'll see "I'll login later" in texts and team chats everywhere. It won't confuse anyone in a quick message, but it's still nonstandard, and it stands out in anything customer-facing or formal.
A real-world fix
Here's a typical onboarding email from an office in Leeds, with errors:
"Your log in details are attached. Please login to the portal before Friday and change your password. If you can't log-in, contact IT."
Corrected:
"Your login details are attached. Please log in to the portal before Friday and change your password. If you can't log in, contact IT."
The first is an adjective before details; the second and third are verbs. Notice that the hyphenated log-in is a noun form in some British writing, never a verb.
A memory trick
If it's a button you press, it's an action; if it's a box you fill, it's a thing. The button says Log in (verb, two words). The box above it is the login field (noun, one word).
Doing = two words. Having = one word. You log in; you have a login.
This exact rule also governs setup vs set up, so mastering one helps you with the other. The pattern extends to backup / back up, checkout / check out and workout / work out.
Practice quiz
Choose the correct form.
- I tried to (login / log in) three times before it worked.
- The (login / log in) screen looks different after the update.
- Remember to (log out / logout) when you use a shared computer.
- She hasn't (loged / logged) in for months.
- Please (sign in / sign-in) at reception when you arrive.
- Make sure the (sign in / sign-in) sheet is on the front desk.
Answers
- log in – a verb after to.
- login – an adjective describing screen.
- log out – a verb after to.
- logged – past participle, double g.
- sign in – a verb (an instruction).
- sign-in – a compound adjective before sheet.
Getting It Right Every Time
Treat the space as a sign of action. Whenever someone is doing the logging, signing or checking, keep the words apart: log in, sign in, log out. When you're naming the details, the page or the button itself, close them up: login, logout, sign-in. Choose one set of terms for any project and stay consistent, and you'll look more careful than half the apps on your phone. For related noun-and-verb pairs in everyday writing, see already vs all ready, which deals with a different kind of spacing confusion.
Frequently asked questions
Is it “log in to” or “log into”?
Traditional style guides prefer “log in to,” because the verb is “log in” and “to” is a separate preposition. “Log into” is very common, especially in American tech writing, and many dictionaries now record it. In formal documentation and edited writing, “log in to” is the safer choice.
What is the difference between “sign in” and “log in”?
In practice, they mean the same thing: to identify yourself to a system, usually with a username and password. “Sign in” sounds slightly friendlier and is preferred by several large tech companies, while “log in” is older and more technical. Pick one and use it consistently, including its opposite (“sign out” or “log out”).
Is it “logged in” or “loged in”?
Write “logged in,” with a double g. The g doubles because “log” is a one-syllable word ending in a single vowel plus a consonant. The same goes for “logging in.”
Should I write “login page” or “log-in page”?
“Login page” is the most common form, especially in American English and in software. Some British publishers hyphenate the noun or adjective as “log-in.” Either is acceptable, but never use the hyphenated or closed form for the verb.
Is “logon” a word?
Yes, “logon” exists as a noun or adjective, mostly in older computing contexts, such as a “logon screen” or “logon script.” The verb is “log on,” two words. In modern consumer software, “login” and “sign-in” have largely replaced “logon.”
Is it “sign-in sheet” or “sign in sheet”?
Write “sign-in sheet” with a hyphen. When the phrase works as an adjective before a noun, it is usually hyphenated. The verb remains two words: “Please sign in at reception.”