Check-in and check in are two correct terms used to describe the process of registering one's arrival or presence, with "check-in" commonly used as a compound adjective and "check in" as a verb phrase in different contexts.

This means the spelling variation of this phrase depends on the context, and both are correct based on the sentence's intended meaning.

Let's take a quick look at the differences between check-in and check in.

Should I Use Check-in or Check In?

According to the Cambridge Dictionary, the correct usage of this phrase is both check-in and check in, which means that the hyphenated and non-hyphenated forms are both acceptable.

However, using these terms interchangeably can lead to errors, highlighting the importance of understanding their use in simple sentences.

How to Use Check-In or Check In

The spelling variation of this phrase depends on the sentence's context. Before using either variation, consider the following factors:

1. Use "Check In" (two separate words):

• As a verb phrase: "Please check in at the front desk when you arrive."
• Referring to the action of registering one's arrival: "Passengers are required to check in at least 30 minutes before the flight."
• In general contexts of arrivals and registrations: "Make sure to check in with the receptionist when you come for your appointment."

2. Use "Check-In" (hyphenated):

• As a compound adjective to describe a process: "The check-in procedure at the hotel was quick and efficient."
• When referring to specific locations or counters: "The airline has a dedicated check-in counter for international flights."
• In technology and online contexts: "Complete the online check-in process before arriving at the airport."

Differences Between Check-In and Check In

As you can see, there are differences in the definitions of these two terms, leading to specific usage, spacing, and context rules, such as the following:

1. Spacing:

• "Check in" is written as two separate words.
• "Check-in" is hyphenated.

2. Usage:

• "Check in" is used as a verb phrase, describing the action of registering one's arrival.
• "Check-in" is often used as a compound adjective to describe related things, such as a "check-in process" or a "check-in counter."

3. Context:

• "Check in" is more commonly associated with travel, hotels, and general arrivals.
• "Check-in" can have broader applications and may be used in various contexts, including technology (for example, online check-in) and events (for instance, conference check-in).

Check-In Sentence Examples

Check-in, the compound adjective version of this phrase, can be used in scenarios like the following:

• Passengers must complete the online check-in process before arriving at the airport.
• The hotel offers a convenient mobile check-in option for guests on the go.
• Please proceed to the conference check-in desk to collect your event materials.
• The airline has a dedicated check-in counter for passengers with special assistance needs.
• We encourage attendees to complete the check-in formalities early to avoid delays.
• The online check-in system allows you to select your seat before the flight.
• Parents are required to accompany minors during the check-in process at the school.
• The hotel's express check-in service is available for guests who prefer a quick arrival process.
• The receptionist will assist you so you can use the check-in app to complete the process.

Check In Sentence Examples

On the other hand, if you want to use the verb version of this phrase, "check in," then consider the following examples:

• Please remember to check in at the front desk upon your arrival.
• Guests can check in starting at 2:00 PM, and check-out time is by 11:00 AM.
• Passengers are advised to check in at least two hours before their scheduled flight.
• We have a new online system that allows you to check in from the comfort of your home.
• Students must check in with the attendance office if they arrive late to school.
• The receptionist will help you check in and provide you with your room key.
• Patients should check in at the registration desk before proceeding to the waiting area.
• During the event, please check in with our staff at the information booth for updates.
• Employees are required to check in upon entering and checking out when leaving the office.

Wrapping Up: Should I Write Check-in or Check In?

Before using either "check in" or "check-in," it's crucial to recognize the grammatical context.

As mentioned earlier, "check-in" is commonly used as a compound adjective, describing processes or locations, while "check in" is a verb phrase describing the action of registering upon arrival.

While both terms are correct, they can't be used interchangeably, and the right choice depends on the role the term plays in your sentence.