Use during with a specific named time period to say when something happened (during the film, during summer); use for with a number or measurement to say how long something lasted (for two hours, for three years).
During and for are both prepositions of time, but they answer completely different questions. During tells you when — it points to a named time frame. For tells you how long — it measures a duration. Mixing them up is a very common mistake at B1–B2 level, and understanding the difference immediately improves your writing and speaking accuracy.
The Core Structural Difference
| Word | Meaning | Follows | Example |
|---|---|---|---|
| during | within / at a point in a named period | a noun / noun phrase (specific period) | She fell asleep during the lecture. |
| for | a measured length of time | a number + time unit | She slept for two hours. |
Using “During”
During is a preposition meaning “at some point within” or “throughout” a named time period. It must be followed by a noun or noun phrase that identifies a specific period — not a number. It answers the question When?
Definition
During connects an event to the time frame in which it occurs. The time frame must be named (the meeting, summer, the war, the film, our holiday) — not measured by a number.
When to use it
- To say something happened within a specific named period
- To say something happened throughout an entire period
- With nouns like: the night, the lesson, the storm, the holidays, his childhood, the match
He checked his phone during the meeting.
It rained during the night.
She learned to swim during the summer.
Many buildings were destroyed during the war.
Please be quiet during the performance.
during + named time period (noun): during the film / during winter / during our trip
Ask yourself: Can I replace it with “at some point within [period]”? If yes → use during.
Common errors with “during”
I waited during two hours.
I waited for two hours. (two hours = measured duration, not a named period)
She worked during many years.
She worked for many years. (many years = measured duration)
Using “For”
For is used to express a measured length of time. It must be followed by a number (or equivalent) and a time unit. It answers the question How long?
Definition
For measures how long an action or state lasts. You always need a quantity: a number, a few, several, many, or a long time followed by a time unit.
When to use it
- To measure how long something lasts
- With number + time unit: for two hours, for three days, for a week, for six months, for years
- With all verb tenses: past simple, present perfect, present simple, future
I waited for two hours.
She has lived here for five years.
We studied for a long time.
He was in hospital for three weeks.
Can you stay for a few days?
for + number/quantity + time unit: for two hours / for a week / for several years
Ask yourself: Am I measuring HOW LONG? If yes → use for.
Common errors with “for”
She slept for the night. (the night = named period → use during)
She slept during the night. (at some point within the night)
She slept for eight hours. (measured duration → use for)
Side-by-Side Comparison
| Word | Answers | Example | Common use |
|---|---|---|---|
| during | When? | during the lesson, during summer | Named events, seasons, historical periods, activities |
| for | How long? | for two hours, for three years | Measured time with all tenses; present perfect especially |
Tricky Cases
Some sentences can use either word, but with a different meaning:
It snowed during the night. (at some point within the night — when)
It snowed for three hours. (measured length — how long)
She cried during the film. (at a point within the film — when)
She cried for an hour after the film. (measured duration — how long)
Replace the phrase with a question: Does it answer “When did it happen?” → use during. Does it answer “How long did it last?” → use for.
During vs For vs While
Learners sometimes also confuse during with while. The difference is grammatical: during is a preposition (followed by a noun); while is a conjunction (followed by a clause with a subject and verb).
She fell asleep during the film. (during + noun)
She fell asleep while she was watching the film. (while + clause)
She fell asleep during she was watching the film.
Memory Tip
During = Definite period — you can name it (the holiday, the war, the lesson).
For = Figure (number) — you can count it (two hours, five years, a week).
If you can put a number in front of it → use for. If it has a name, not a number → use during.