"Check-in" vs "Check in": When to Use Each Form

The difference between "check-in" and "check in" depends on how you're using it in a sentence. Let's break down when to use each form to help you write with confidence.

Key Differences Between Forms

Check-in (hyphenated): Used as a noun or adjective
Check in (two words): Used as a verb
Checkin (one word): Incorrect form - never use this

When to Use "Check-in"

Use the hyphenated form when it's:

A noun (the act of registering)
An adjective describing something

Examples:

Your check-in time is 3 PM
Please complete the check-in process
Visit the check-in counter

When to Use "Check in"

Use two separate words when it's:

A verb (the act of registering)
Part of a verbal phrase

Examples:

Please check in at the front desk
When do we check in for our flight?
I need to check in with my supervisor

Examples in Different Contexts

Form	Example	Usage Type
Check-in	The check-in desk is there	Noun
Check-in	Complete your online check-in	Noun
Check in	We will check in tomorrow	Verb
Check-in	Your check-in baggage	Adjective

Quick Tips to Remember

If you can replace it with "registration," use check-in
If you can add "to" before it, use check in
If it describes something, use check-in
If it's an action, use check in

Common Usage Scenarios

Hotel Context:

The check-in counter (noun)
Please check in here (verb)
Your check-in time (adjective)

Airport Context:

Online check-in (noun)
Check in your bags (verb)
Check-in procedures (adjective)

FAQ About Check-in vs Check in

Q: Is "checkin" ever correct? A: No, "checkin" as one word is never correct in standard English.

Q: What about in digital contexts? A: The same rules apply - use "check-in" for nouns and adjectives, "check in" for verbs.

Q: Can I use these terms in informal writing? A: Yes, but the same grammatical rules still apply.

Conclusion

Remember:

Use check-in for nouns and adjectives
Use check in for verbs and actions
Never use "checkin" as one word
When in doubt, think about how you're using the term