Shifts per month to hours per week
Updated October 8, 2026 · 2 min read
Multiply shifts per month by hours per shift, then multiply by 12 and divide by 52 to get hours per week. For example, 14 shifts of 9 hours is 126 hours a month, or about 29.1 hours a week.
The arithmetic
- Hours a month = shifts a month × hours a shift
- Hours a week = hours a month × 12 ÷ 52
- Hours a year = hours a month × 12
A year has 52 weeks and 12 months, so a month averages 52 ÷ 12, about 4.33 weeks. The IRS uses the same ratio when it treats 130 hours of service in a month as the monthly equivalent of 30 hours a week.
To go from weeks to months, multiply by 52 and divide by 12. Three 10-hour shifts a week is 30 hours a week, which works out to 13 shifts and 130 hours a month.
Worked examples
| Shifts a month | Hours a shift | Hours a month | Hours a week | Hours a year |
|---|---|---|---|---|
| 14 | 9 h | 126 h | 29.1 h | 1,512 h |
| 16 | 8 h | 128 h | 29.5 h | 1,536 h |
| 12 | 12 h | 144 h | 33.2 h | 1,728 h |
| 15 | 10 h | 150 h | 34.6 h | 1,800 h |
| 18 | 9 h | 162 h | 37.4 h | 1,944 h |
A published figure works the same way. One EM residency reports that first-year residents average 180 hours a month: 180 × 12 ÷ 52 is about 41.5 hours a week.
Two common mistakes
- Dividing by 4. A month is not 4 weeks, and dividing by 4 overstates weekly hours by about 8%: 126 hours a month becomes 31.5 hours a week instead of 29.1.
- Treating a 28-day block as a month. In the same 2023 survey, 73.2% of responding EM residency programs used thirteen 28-day blocks a year. A block is exactly 4 weeks, so divide block hours by 4 and multiply by 13 for a year: 19 shifts of 9 hours is 171 hours a block, 42.75 hours a week and 2,223 hours a year. Dividing by 4.33 would show 39.5.
Night hours and the calculator
To see how much of your month falls at night, count the hours between 23:00 and 07:00. A 23:00 to 08:00 shift has 8 of its 9 hours in that window, so 3 such nights in the 14-shift month above put 24 of 126 hours, 19%, at night.
Calculator · runs in your browser, nothing is sent
- Hours a month
- 126 h
- Hours a week
- 29.1 h
- Hours a year
- 1,512 h
- Night hours
- 19%
A week is 12/52 of a month (about 4.33 weeks a month). Night hours assume each night shift covers up to 8 hours between 23:00 and 07:00.
The calculator uses the same 12 ÷ 52 conversion and counts up to 8 hours of each night shift as night hours. My hours works from your real schedule instead: bring in a calendar link or .ics file from any scheduling app to see hours per week, nights and quick returns.
Common questions
- Why not divide monthly hours by 4?
- Because a month averages about 4.33 weeks. Dividing by 4 overstates weekly hours by about 8%.
- How many hours a month is 40 hours a week?
- About 173.3 hours: 40 × 52 ÷ 12.
- Should time after the shift count?
- If you stay to chart or hand off, that is work too. ACGME counts it toward residents' weekly hours, so add it to hours a shift if you want the true total.
See your own shifts this way.
Bring in your schedule from any scheduling app with its calendar link. Capillary charts your hours, nights, quick returns and hardest shifts. Only you can see it.