To express how often something happens—like "twice a week" or "once a day"—Swedish uses the prepositions i and om followed by the definite form of the time word. Which preposition you use depends entirely on the specific unit of time.
Frequency with "om"
Use the preposition om when measuring frequency by the day. The core words are dagen (the day) and dygnet (the 24-hour period).
To state the number of occurrences, use the phrase en gång (one time/once) or its plural gånger (times).
| I brush my teeth twice a day. | Jag borstar tänderna två gånger om dagen. |
| He shaves once a day. | Han rakar sig en gång om dagen. |
| One takes a pill four times a day. | Man tar en tablett fyra gånger om dygnet. |
Frequency with "i"
For most other common units of time, you will use the preposition i. This includes timmen (the hour), veckan (the week), and månaden (the month). This pattern is used for both recurring habits and measuring rates (like an hourly wage).
| How much do you earn an hour? | Hur mycket tjänar du i timmen? |
| I pay the rent once a month. | Jag betalar hyran en gång i månaden. |
| We love the forest, so we walk there twice a week. | Vi älskar skogen, så vi promenerar där två gånger i veckan. |
Years and other rates
When you talk about events that happen yearly, you switch back to om for året (the year). Remember that the rules for i and om remain exactly the same whether you are counting how many times you travel or stating a daily or hourly rate.
| We travel to Sweden three times a year. | Vi reser till Sverige tre gånger om året. |
| He earns a hundred crowns an hour, and the salary is good. | Han tjänar hundra kronor i timmen och lönen är bra. |
| I pay a hundred crowns a day for the walk. | Jag betalar hundra kronor om dagen för promenaden. |
