Weeks to Months Converter
| Duration | Weeks | Months |
|---|---|---|
| Full-term pregnancy | 40 wk | 9.21 mo |
| Standard annual lease | 52 wk | 11.97 mo |
| Half marathon training plan | 12 wk | 2.76 mo |
| Six-month subscription | 26 wk | 5.98 mo |
| A semester | 16 wk | 3.68 mo |
| One year | 52.14 wk | 12 mo |
One month is 4.345 weeks on average - because 52.143 weeks per year divided by 12 months gives 4.345, not the 4 that most quick mental math assumes. The gap matters: 40 weeks of pregnancy is 9.2 months (not 10), a 52-week lease is 11.96 months (almost but not quite a year), and a 26-week project is 5.98 months. Type either unit and the converter lands the other.
The weeks-to-months conversion is inherently approximate because months have different lengths - 28 to 31 days - while weeks are always 7 days. The 4.345 factor is the year-average, which is the right number for estimating rent, pregnancy progress, project timelines and subscription billing. The table below anchors the common durations people convert.
How to use
- Type the weeks from your project plan, medical timeline or lease - months appear instantly.
- Or run the reverse: a 6-month subscription is 26.07 weeks of coverage.
- Remember: 4 weeks is NOT a month - the gap compounds, so always use 4.345 for accuracy beyond a few weeks.
Frequently asked questions
How many weeks is 1 month?
On average, 4.345 weeks - because a year has 52.143 weeks (365.25 ÷ 7) and 12 months, giving 4.345 weeks per month. The shortcut '4 weeks = 1 month' is off by 8.6 percent, which matters for anything longer than a few weeks. A 40-week pregnancy at 4.345 is 9.2 months, not the 10 months the 4-week shortcut would suggest.
How many weeks in a year?
52 weeks and 1 day in a common year (365 ÷ 7 = 52.14), and 52 weeks and 2 days in a leap year (366 ÷ 7 = 52.29). Over the four-year leap cycle the average is 52.179 weeks per year. This is why annual salaries divided by 52 give slightly different weekly figures than dividing by 52.143 - the difference is the leap-day spillover.
Why is 4 weeks not a month?
Because four weeks is 28 days, but only February in a non-leap year is exactly 28 days - the other months run 29 to 31 days. Over a year the extra 1-3 days per month add up to 5.25 extra days, which is why 12 months x 4 weeks = 48 weeks, not the 52 the year actually has. The missing 4 weeks are spread across the year, invisible in any single month but critical over a lease or pregnancy.
How many weeks is 6 months?
About 26.07 weeks - six times the 4.345 average. This is why biweekly payments (every two weeks) make 26 payments a year while semimonthly payments (twice a month) make only 24: the 2-payment gap is the same 8.6 percent difference between 4 weeks and a real month, and it adds up to a full extra mortgage payment over a decade.
Do pregnancy weeks convert exactly to months?
No - obstetricians work exclusively in weeks precisely because months are uneven. The 40-week full-term figure equals about 9.2 calendar months, which is why 'nine months' is a simplification: the weeks are the precise unit, counted from the last menstrual period rather than conception. The converter gives the general population's approximation for everyone else in the conversation.