Practice
Unless or until: what's the difference?
Wait until the store opens. Leave now unless you need help. The first sentence gives a time. The second gives a condition.
Choose until for an endpoint in time and unless for a condition or exception, including in ordinary future sentences.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
unless and until /ənˈles ən ənˈtɪl/
The short answer
Use until for time: We waited until the rain stopped. Use unless for a condition: We will cancel the walk unless the rain stops.
Please wait until the screen shows a green message.
Why it works: Until marks the point when the waiting can end.
5 more examples
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Don't open the meeting room until the coordinator arrives.
The arrival is the point when opening the room can happen.
Not this:Don't open the meeting room
unless the coordinator asks you to. What changes: The request is a condition for opening the room. The sentence gives no time endpoint. -
The library is open until 8 p.m.
Until shows when the library's open period ends.
Not this:The library is open
unless there is an emergency. What changes: An emergency is an exception that can change whether the library is open. -
I won't sign the form until I read it.
Reading comes before the possible signing, so the clause marks an order in time.
Not this:I won't sign the form
unless I read it. What changes: Reading is a necessary condition for signing. The sentence does not promise that signing follows immediately. -
Stay on this page until the upload ends.
The upload ending gives the endpoint for staying on the page.
Not this:Stay on this page
unless the support team tells you to leave. What changes: The support team's message is the exception to the instruction. -
Wait until I call your name.
The call is a future point that ends the wait.
Not this:Don't speak
unless I call your name. What changes: The call gives permission to speak. It is a condition, not a length of time.
Read the full guide
Ask whether the sentence has a timeline or a condition. Until points to the time when a wait, action, or state ends. Unless says that a result changes only if a stated condition is met.
Choose time or condition
A message can tell you when to wait, or it can tell you what must happen. Use until for the time question. Use unless for the condition question. This first choice usually gives you the right word.
We waited until the doors opened.
The doors opening is the point when the waiting ends.
Which word fits a time endpoint: We will stay here ___ the bus arrives?
Use until: We will stay here until the bus arrives.
Use until for an endpoint
Until shows that an action or state continues up to a time. Put it before a clock time, a day, or an event. The event can be something that happens later.
The office is closed until Monday.
Monday is the point when the closed period ends.
Choose the word for a waiting period: Don't start dinner ___ everyone is home.
Use until: Don't start dinner until everyone is home.
Use unless for an exception
Unless gives the condition that changes the result. It often means except if or if not. Think of it as the one situation that stops the main statement from being true.
The package will arrive tomorrow unless the road is closed.
A road closure is the exception that can stop tomorrow's delivery.
Choose the word for a condition: You cannot enter ___ you show an ID card.
Use unless: You cannot enter unless you show an ID card.
Compare the same action
A negative main clause can make both words look similar. The meaning still changes. Until puts events in order. Unless gives a requirement and does not say exactly when the action will happen.
I won't leave until Sam calls.
Sam's call is the event that ends the waiting. I won't leave unless Sam calls means that Sam's call is required before I leave.
Which word shows a requirement: I won't use the machine ___ someone explains it first?
Use unless: I won't use the machine unless someone explains it first.
Keep future clauses in the present
When the main clause talks about the future, English usually keeps the verb after until or unless in the present. The future meaning comes from the whole sentence. Do not add will inside these ordinary clauses.
We will leave unless the rain stops.
The main clause has will leave. The clause after unless uses stops, not will stop.
Complete the future sentence: We will wait until the doctor ___.
Use arrives: We will wait until the doctor arrives.
Before you go
Remember this
Use until to show an endpoint in time. Use unless to show a condition or exception. If the sentence answers when an action can end, choose until. If it answers what must happen for a different result, choose unless.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Unless or until: what's the difference?"
Are unless and until interchangeable?
No. Until refers to a point in time, so it tells you how long an action or state continues. Unless introduces a condition or exception. In Wait until the lights change, the lights give an endpoint. In Go unless the lights are red, the red light is a condition that changes the instruction.
Don't open the meeting room until the coordinator arrives.
Can I use until with a clock time?
Yes. Use until before a time when something continues up to that point. The museum is open until 5 p.m. means that its open period ends at 5 p.m. You can also use until before an event, such as until the meeting ends, when the event supplies the time point.
Don't open the meeting room unless the coordinator asks you to.
Does unless mean the same as if not?
In many sentences, yes. Unless you charge the battery, the device will stop can be understood as If you do not charge the battery, the device will stop. Unless is useful when you want to state the exception in one word. Check the whole sentence, because the condition must fit the intended result.
The library is open until 8 p.m.
Can until and unless refer to the future?
Yes. Use them in future situations, but ordinary clauses after until and unless usually take a present verb form. Write We will wait until the train arrives and Unless the train arrives soon, we will leave. The future meaning comes from the main clause and the situation.
The library is open unless there is an emergency.
Should I use until for a deadline?
Usually use by when an action must be complete before a deadline. Send the application by Friday means that it must arrive no later than Friday. Use until when something continues up to a point, as in The office is open until Friday. The words answer different time questions.
I won't sign the form until I read it.