How it's calculated
months = weeks ÷ 4.348125
4.348125 = average weeks per month (30.44 days ÷ 7). Reverse: weeks = months × 4.348125.
Common values
| Weeks | Months |
|---|---|
| 4 wk | 0.92 mo |
| 8 wk | 1.84 mo |
| 13 wk | 2.99 mo |
| 26 wk | 5.98 mo |
| 40 wk | 9.20 mo |
Common questions
How many weeks are in a month?
On average a month has 4.348 weeks, found by dividing 365.25 days a year by 12 months and then by 7 days.
Why is 40 weeks of pregnancy called 9 months?
Forty weeks works out to about 9.2 average months, so pregnancy is commonly rounded to nine months even though it runs slightly longer.