Tally My ShiftHow many work hours are in a biweekly, semimonthly or monthly pay period
Updated · Worked examples use whole minutes
A full-time 40-hour schedule gives 80 hours in a biweekly pay period, 86.67 hours on average in a semimonthly period and 173.33 hours on average in a calendar month. Biweekly periods always contain 14 days. Semimonthly and monthly periods change length with the calendar.
Calculate it step by step
- Find the first and last date covered by the pay statement, not the payment date.
- List the shifts you worked between those dates, including any overnight shift that started on the last date.
- Add the worked hours for exactly those dates.
- Compare the total with the worked-hours lines on the statement, keeping leave and premium lines separate.
Worked example
A biweekly period from Monday, March 2 to Sunday, March 15, 2026 with eight-hour weekday shifts contains 10 weekdays, or 80 hours. The semimonthly period from March 16 to March 31, 2026 contains 12 weekdays, or 96 hours, well above the 86.67-hour average.
Check your own shifts in the time card calculator
Scheduled hours per pay period by weekly hours
| Hours a week | Biweekly | Semimonthly average | Monthly average |
|---|---|---|---|
| 20 | 40 | 43.33 | 86.67 |
| 30 | 60 | 65.00 | 130.00 |
| 37.5 | 75 | 81.25 | 162.50 |
| 40 | 80 | 86.67 | 173.33 |
Averages use 52 weeks a year. Actual periods depend on how many scheduled days fall between the start and end dates.
Why does a real pay period differ from the average?
The averages come from 40 × 52 = 2,080 hours a year. Dividing by 24 semimonthly periods gives 86.67 hours, and dividing by 12 months gives 173.33 hours.
These averages describe a schedule, not a particular period. A 31-day month can contain 23 weekdays, or 184 hours at eight hours a day, while February in a non-leap year contains exactly 20 weekdays, or 160 hours.
Twenty-six biweekly periods cover 364 days, one or two days short of a year. That is why a calendar year occasionally contains 27 biweekly paydays. Compare the dates printed on the statement rather than assuming a fixed number of hours.
Quick answers
How many hours is full time biweekly?
On a 40-hour week, a biweekly period has 80 scheduled hours. On a 37.5-hour week it has 75.
How many work hours are in a month?
On a 40-hour week the yearly average is 173.33 hours a month. A particular month ranges from 160 hours in a 20-weekday February to 184 hours in a month with 23 weekdays.
What is the difference between biweekly and semimonthly?
Biweekly means every two weeks, 26 periods of 14 days a year. Semimonthly means twice a month, 24 periods whose length varies from 13 to 16 days.