When you want to express how long an action lasts, Swedish uses two different time prepositions depending on whether the action is actively happening or if you are describing a period without the action: i and på.
Ongoing duration with "i"
To state how long an action or state has been continuously happening, use the preposition i. This corresponds to the English "for" when talking about duration.
| The boy has waited in the queue for an hour. | Pojken har väntat i kön i en timme. |
| She has been awake for sixty hours. | Hon har varit vaken i sextio timmar. |
You will also use i when talking about an inability to endure an action for a given amount of time.
| The child cannot be quiet for a minute. | Barnet kan inte vara tyst i en minut. |
Time elapsed with "på"
When you want to express how long it has been since an event last occurred, use på. You will almost always see this used in negative sentences to mean that you have not done something "in" or "for" a certain amount of time.
| I have not slept for a whole day and night! | Jag har inte sovit på ett helt dygn! |
| We have not seen him in an eternity. | Vi har inte sett honom på en evighet. |
| The dog has not eaten in several hours. | Hunden har inte ätit på flera timmar. |
Endurance and patience
When talking about endurance, you will frequently encounter verbs like kämpa (to struggle) and klara (to manage). The same preposition rules apply: use i for the duration of an ongoing struggle or test of endurance, and på for how long someone has gone without doing something.
| He has struggled with the project for an eternity. | Han har kämpat med projektet i en evighet. |
| Can you manage to be quiet for ten seconds? | Klarar du att vara tyst i tio sekunder? |
| The doctor has not lost his patience in a week. | Läkaren har inte tappat tålamodet på en vecka. |