Time in Norwegian is carved up by four small prepositions — i, på, om, and ved — plus the framing constructions fra … til and for … siden ("ago"). For a quick either/or on i vs på, see the decision guide i vs på; this page is the systematic reference covering the whole time system, including om and the cases the quick guide doesn't reach. The deepest trap, which English speakers hit constantly, is the contrast between i tre timer ("for three hours, duration") and på tre timer ("in three hours, completion") — covered in full below.
i — duration, the current period, and years
i does three time jobs. First and most important, i marks duration — how long something lasts. This is English "for":
Vi ventet i tre timer på flyplassen.
We waited for three hours at the airport.
Han har bodd i Norge i to år.
He's lived in Norway for two years.
Jeg skal være borte i en uke.
I'll be away for a week.
Note: do not translate English "for" with a Norwegian for here. Duration is i, full stop. (Norwegian for exists but does other work; see the trap in Common Mistakes.)
Second, i marks "this current period" in a cluster of fixed adverbials — i dag, i kveld, i morges, i fjor, i sommer. These point at the relevant instance of a period (today's day, this evening, this past summer):
Hva skal vi gjøre i kveld?
What shall we do this evening?
Jeg sov dårlig i natt.
I slept badly last night.
Vi var i Hellas i fjor.
We were in Greece last year.
Det snødde mye i vinter.
It snowed a lot this winter.
A subtlety worth flagging: with seasons, i sommer can mean this (coming or just-past) summer depending on context, while om sommeren means in summers, habitually — more on that under om below.
Third, i marks years: i 2024, i 1990.
Hun ble født i 1998 og flyttet hit i 2019.
She was born in 1998 and moved here in 2019.
på — named days, and completion within a span
på does two main time jobs. First, named days and parts of named days take på — this is English "on":
Vi sees på fredag.
See you on Friday.
Bursdagen min er på søndag i år.
My birthday is on Sunday this year.
Kan vi ta det på mandag i stedet?
Can we do it on Monday instead?
Second — and this is the trap — på marks the span within which an action is completed. This is English "in" (as in "I did it in an hour"):
Han lærte seg norsk på seks måneder.
He learned Norwegian in six months. (completed within that span)
Jeg klarte oppgaven på ti minutter.
I finished the task in ten minutes.
There is also a regional habitual use — på morgenen / på kvelden for "in the mornings / evenings" — common especially in some western and northern dialects, where standard Eastern usage prefers om morgenen / om kvelden (see om). Both are understood everywhere.
The duration-vs-completion trap: i vs på
This is the contrast that catches every English speaker. Compare:
Jeg leste boka i to timer.
I read the book for two hours. (and maybe didn't finish — pure duration)
Jeg leste boka på to timer.
I read the book in two hours. (finished it within that span — completion)
Same numbers, opposite meaning. i to timer measures how long the reading lasted; på to timer measures how long it took to get through the book. English makes exactly this distinction with for vs in — so the logic is identical, but the Norwegian prepositions look "swapped" relative to your instinct, which is why it trips people up.
Vi malte huset på en helg.
We painted the house in one weekend. (got it done within)
Vi malte i en helg, men ble ikke ferdige.
We painted for a weekend but didn't finish. (just duration)
om — future "in", and habitual times of day
om also does two jobs. First, om = "in X time from now", pointing into the future — English "in" with a future sense:
Toget går om ti minutter.
The train leaves in ten minutes.
Vi flytter til Tromsø om en måned.
We're moving to Tromsø in a month.
Jeg ringer deg om en time.
I'll call you in an hour.
This is the cleanest place to confuse i and om, because both can render English "in." Keep them apart by direction in time: om looks forward ("in two days = two days from now"), while a span you measure backward or as pure duration is i:
Eksamen er om to dager.
The exam is in two days. (two days from now — future)
Jeg har lest om to dager... nei — i to dager.
(self-correction reminder) duration is 'i to dager', not 'om'.
Second, om marks habitual times of day and recurring periods — English "in the mornings / in winter, as a rule":
Jeg drikker alltid kaffe om morgenen.
I always drink coffee in the morning(s).
Det er kaldt og mørkt her om vinteren.
It's cold and dark here in (the) winter.
Hun jobber om natta og sover om dagen.
She works at night and sleeps during the day.
Contrast this habitual om vinteren ("in winters, generally") with the specific i vinter ("this winter"). That i/om pair is a genuinely useful distinction Norwegian draws that English blurs.
ved — at a clock point, and around an edge of time
ved pins a moment to a point on the clock or the edge of a period — English "at" or "around":
Vi møtes ved midnatt.
We're meeting at midnight.
Han våknet ved soloppgang.
He woke at sunrise.
For clock times more generally, the everyday word is the klokka construction (klokka tre = at three o'clock), with ved reserved for "around/at" a salient point like midnight, noon, or dawn.
fra … til and for … siden
Two framing constructions complete the system. fra … til spans a start and an end point ("from … to/until"); see fra: From and til: To, Until, Of, For:
Butikken er åpen fra ni til fem.
The shop is open from nine to five.
Jeg jobber fra mandag til fredag.
I work from Monday to Friday.
for … siden is the fixed frame for "ago" — note that it wraps around the time phrase:
Vi flyttet hit for tre år siden.
We moved here three years ago.
Hun ringte for ti minutter siden.
She called ten minutes ago.
Quick reference
| Sense | Preposition | Example |
|---|---|---|
| Duration ("for") | i | i to timer, i en uke |
| This current period | i | i dag, i kveld, i fjor, i sommer |
| Years | i | i 2024 |
| Named days ("on") | på | på mandag, på fredag |
| Completion within ("in") | på | på tre dager |
| Future "in X from now" | om | om en time, om en uke |
| Habitual time of day / season | om | om morgenen, om vinteren |
| At a clock point | ved | ved midnatt |
| "Ago" | for … siden | for tre år siden |
| Span start–end | fra … til | fra ni til fem |
Common Mistakes
The big errors: translating "for" literally for duration, confusing i (duration / this period) with om (future), and reaching for på where habitual om is wanted.
❌ Jeg ventet for to timer.
Incorrect — duration is not Norwegian 'for'.
✅ Jeg ventet i to timer.
I waited for two hours.
❌ Toget går i ti minutter.
Wrong sense — this says the train runs FOR ten minutes (duration).
✅ Toget går om ti minutter.
The train leaves in ten minutes (from now).
❌ Jeg leste boka i to timer og ble ferdig.
Mismatched — completion needs på, not duration i.
✅ Jeg leste boka på to timer.
I read the book in two hours. (completed within)
❌ Vi sees i fredag.
Incorrect — named days take på.
✅ Vi sees på fredag.
See you on Friday.
❌ Jeg drikker kaffe i morgenen hver dag.
Incorrect — habitual time of day takes om (i morges = 'this past morning', a different meaning).
✅ Jeg drikker kaffe om morgenen hver dag.
I drink coffee in the morning every day.
Key takeaways
- i = duration (i to timer), this current period (i dag, i fjor, i sommer), years (i 2024).
- på = named days (på mandag) and completion-within (på tre dager).
- om = future "in X from now" (om en time) and habitual times (om morgenen, om vinteren).
- ved pins a clock point (ved midnatt); for … siden = "ago"; fra … til = a span.
- Watch the swaps: English "for"↦i, English "in"↦på (completion) or om (future). It is på and om with å where shown — never "pa."
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- i vs på: In vs On/AtA2 — Use i for enclosed spaces, countries and towns, and på for surfaces, institutions-as-activity and islands — but accept that much of the i/på choice is fixed collocation you must memorise.
- i vs på: PlaceA2 — The full systematic range of i (inside, countries, cities) vs på (surfaces, institutions-as-activity, islands, many towns) for location — with the collocation lists you must memorise.
- Time Adverbs: nå, da, snart, allerede, ennåA2 — The Norwegian temporal adverbs — nå/da (now/then), allerede vs. ennå (already vs. still/yet), fortsatt, snart, straks — and the tense pairings English speakers must relearn.
- fra: FromA2 — fra cleanly means 'from' — spatial origin (fra Norge), source and sender (et brev fra mor), the start of a time span (fra mandag), and the fra…til frame — with a clear contrast to av.
- til: To, Until, Of, ForA2 — til covers direction (til Oslo), the everyday spoken possessive (boka til Kari), time limits (til klokka tre), recipients (en gave til mor), and a set of fixed phrases — with the noun-form rules English speakers miss.
- Advanced Time Prepositions: i, på, om, ved, innenB1 — The fuller B1 time system — i (duration), på (named days, completion-within), om (future point, habitual), ved (a point on the clock), innen (by a deadline), i løpet av / under (during) — and the deadline-vs-duration trap where innen has no single English word.