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When vs while
When marks a moment or a short event (when the phone rang); while marks a stretch of time running alongside something else (while I was cooking).
Quick rule
A point in time, an age, or a future moment (when you arrive)? When. A stretch of time running alongside something else (while I was cooking)? While.
Links an action to a point in time: a short event that breaks in (when the phone rang), ages and stages of life (when I was a kid), and the future (when you arrive). Also a question word.
During the time that something else is going on (while I was cooking). It also contrasts two facts, like whereas. As a noun, a while is a period of time.
Why it trips people up
When and while overlap with a longer background action: when I was cooking and while I was cooking both work. They split elsewhere. When handles points in time, ages, and questions; while handles two things lasting together and contrasts (while I prefer tea).
How each one works
When
The short event that breaks in
I was taking a shower when the lights went out.
An age or stage of life
We lived in Bogotá when I was a kid.
Future: when + present
Text me when you get to the hotel.
Question: When?
When did you start working here?
While
The longer background
Someone stole my bike while I was at the movies.
Two long actions at once
I listen to podcasts while I cook dinner.
Contrast, like whereas
My sister loves the beach, while I prefer the mountains.
While + past continuous
She checked her email while the coffee was brewing.
What comes next
longer action plus when plus short event
We were watching TV when my cousin called.
when plus age or stage of life
When she was sixteen, she got her first job.
when plus present (for the future)
I'll call you when I finish.
while plus ongoing action
While you were sleeping, it snowed.
while plus -ing
He lost his keys while running in the park.
Almost the same
When the movie started, I turned off my phone.
A moment: it starts, then I turn it off.
While the movie was playing, I fell asleep.
A stretch of time: I fell asleep at some point.
He cried when he read the letter.
Reading it made him cry: told as one moment.
He cried while he was reading the letter.
He cried during the reading: a stretch of time.
In a conversation
- A:
When did you learn to cook so well?
- B:
While I was living alone in Toronto. I had no choice!
- A:
I burned the rice last night while I was texting.
- B:
Ha! Next time, ask me for a lesson.
Common mistakes
Wrong: Show your ID while boarding the plane.
Right: Show your ID when boarding the plane.
Boarding is the moment you need it, not a stretch of time. Cambridge lists while buying a bus ticket as a typical error for the same reason.
Wrong: My dad likes jazz, when my mom likes salsa.
Right: My dad likes jazz, while my mom likes salsa.
For a contrast between two facts, use while (or whereas). When links events in time; it does not contrast.
Memory trick
A moment (it rang, she arrived) or a stage of life (when I was ten)? When. Something that lasts while something else happens (I was cooking)? While. Asking about time? When; while is not a question word.
It depends
- When both work
- With a longer background action, both are fine: When I was walking home, I saw Ana or While I was walking home... Cambridge and Swan list this shared use.
FAQ
When or while with past continuous?
Use while for the longer background action and when for the short one that breaks in: While I was cooking, the phone rang, or I was cooking when the phone rang.
Can while mean whereas?
Yes. While can contrast two facts: Some people love winter, while others hate it. Cambridge gives this use. When cannot do it.