<em>During</em> answers 'when?' and takes a named period or event: 'She called during the interval.' <em>For</em> answers 'how long?' and takes a length of time: 'She talked for ten minutes.' One locates the event; the other measures it.
The core difference
Both are prepositions, and both are followed by nouns, which is why they get muddled. What differs is the kind of noun.
- During takes a named stretch of time or an event: during the summer, during the flight, during Ramadan, during the presentation.
- For takes a measured quantity: for two hours, for a fortnight, for ages, for the whole of August.
The test
Ask which question the phrase answers. 'When did it happen?' → during. 'How long did it last?' → for.
Second check: can you put a number in front? 'Two hours', 'three days', 'five minutes' — a countable amount of time takes for. A named period like 'the meeting' or 'the war' takes during.
Both in one sentence
They often sit happily together, doing different jobs:
- 'The power went out during the storm for about four hours.'
- 'During the trial he was held for eleven weeks.'
- 'She slept for ten hours during the flight.'
That last one is worth studying. During the flight tells you when the sleeping happened; for ten hours tells you how much of it there was.
Where it goes wrong
The classic error is during with a measured quantity: 'I studied during three hours.' That should be 'for three hours'. This mistake is very common among speakers of languages where a single word covers both jobs — Spanish, French and German all handle it differently from English.
The reverse — for with a named event — is rarer but does occur: 'for the meeting' is fine when it means purpose ('I prepared for the meeting'), but not when you mean 'while the meeting was on', which needs during.
The overlap case
When a period is both named and measurable, either can work with a slight change of emphasis. 'We were away for the summer' stresses the length of the absence; 'we were away during the summer' stresses when it fell. Similarly, 'for the whole meeting' means from start to finish, whereas 'during the meeting' allows for just part of it.
If you specifically mean the entire span, for the whole or throughout is clearer than during, which readers may take to mean 'at some point within'.
Frequently Asked Questions
Is it 'during two hours' or 'for two hours'?
'For two hours.' A measured amount of time always takes 'for'. 'During' needs a named period, such as 'during the lesson'.
Is it 'during the summer' or 'for the summer'?
Both are correct but mean slightly different things. 'During the summer' says when something happened; 'for the summer' says it lasted the whole season.
Which one do I use with a holiday, like Christmas?
'During Christmas' if you mean at some point over the period, and 'for Christmas' if you mean the purpose or the full stretch — 'she came home for Christmas'.