Dans vs en (time expressions)
The short answer
En measures how long something takes to complete: je l’ai fait en dix minutes. Dans measures how long from now until it starts: je pars dans dix minutes. Swapping them does not make the sentence clumsy: it makes it say something else entirely.
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At a glance
En or Dans?
| Compare | EnHow long it takes. Duration of the task. | DansHow long until it starts. Delay from now. |
|---|---|---|
| What it measures | The time the action occupies | The gap before the action begins |
| English equivalent | in, within, it took me | in, in … time |
| Typical tense | Past: je l’ai lu en deux heures | Future: je pars dans deux heures |
| The question it answers | How long did it take? | When? |
| Example pair | Je le fais en une heure. | Je le fais dans une heure. |
| Meaning of that pair | It takes me an hour to do. | I’ll do it an hour from now. |
How to choose
Ask these, in order
- 1
Are you saying how long the task occupies?
En. It measures the work itself.
Elle a écrit le rapport en trois heures.
She wrote the report in three hours.
NBThree hours of writing. That is what the sentence measures.
- 2
Are you saying when something will happen, counting from now?
Dans. It measures the wait, not the work.
Le train part dans vingt minutes.
The train leaves in twenty minutes.
- 3
Could you replace the English with “it took…”?
En. That phrasing only fits the duration reading.
On y va en deux heures par l’autoroute.
It takes two hours to get there on the motorway.
- 4
Could you replace the English with “… from now”?
Dans. That phrasing only fits the delay reading.
Je te rappelle dans cinq minutes.
I’ll call you back in five minutes.
Side by side
Each one, in full
When to use en
How long it takes. Duration of the task.
En measures the time a task takes from start to finish. It sits naturally with past tenses, because completed work is what usually gets measured, and it answers the question combien de temps ?
It is also the preposition for months, seasons and years used on their own: en mars, en été, en 2026. The exception is spring, which takes au printemps because printemps begins with a consonant: a small irregularity worth knowing.
J’ai fini l’exercice en dix minutes.
The exercise took me ten minutes.
On peut y aller en une demi-heure.
We can get there in half an hour.
Il est né en septembre.
He was born in September.
NBThe month use, unrelated to duration but sharing the word.
When to use dans
How long until it starts. Delay from now.
Dans counts forward from the moment of speaking. It goes with future events almost by definition, and it answers the question quand ? rather than combien de temps ?
Dans also has a purely spatial meaning: dans la boîte, dans la rue, which is the sense learners meet first. The time use is an extension of it: a point inside a period ahead of you.
La réunion commence dans dix minutes.
The meeting starts in ten minutes.
Dans deux ans, elle aura fini ses études.
In two years she’ll have finished her studies.
Rappelle-moi dans la matinée.
Call me back during the morning.
NBWith a named period rather than a count, dans means “sometime within”.
Mistakes to avoid
What learners actually get wrong
Je pars en cinq minutes.
Je pars dans cinq minutes.
En cinq minutes would mean your departure takes five minutes to carry out. The sentence is grammatical and means something absurd, which is why this pair is worth learning properly rather than approximately.
J’ai écrit la lettre dans une heure.
J’ai écrit la lettre en une heure.
The past tense makes the intended meaning obvious, but dans still says the writing began an hour from the moment of speaking, which cannot be reconciled with a past tense.
Il arrive en dix minutes.
Il arrive dans dix minutes.
Arriving is a point, not a stretch, so it cannot occupy ten minutes. Verbs that name an instant, arriver, partir, commencer, will almost always take dans.
Je serai prêt en une heure.
Je serai prêt dans une heure.
If you mean an hour from now, it is dans. En une heure is also correct French and says something else: that getting ready occupies an hour of work. When you are giving a deadline, you want dans.
Now use it
Prépositions à, de, en, dans
Places, times and the au / du / aux contractions. Reading a rule and being able to apply it are different skills, and only one of them shows up when you speak.
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Questions
Asked and answered
- Does English make this distinction?
- It uses in for both, which is exactly why the pair is hard. “I’ll do it in an hour” and “I did it in an hour” rely on tense to disambiguate. French marks it in the preposition instead, so the information you would get from context has to be chosen explicitly.
- What about pendant?
- Pendant measures a finished stretch without implying completion: j’ai travaillé pendant deux heures says how long you worked, not that the task finished. En implies the job was done inside that time. J’ai lu le livre en deux heures means you finished it; pendant deux heures does not.
- Is dans always about the future?
- In the time sense, effectively yes, because it counts forward from the moment of speaking. In past narration you would use après or au bout de instead: au bout de dix minutes, il est parti. Dans dix minutes inside a past story would be jarring.