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Twice-a-month pay period · 2026Semi-Monthly Timesheet Calculator
Add up the hours you worked in a twice-a-month pay period — the 1st–15th or the 16th–end of the month. Enter each day's hours and get your total, decimal hours and gross pay, with the overtime gotcha explained.
How the semi-monthly pay period works
Semi-monthly means you're paid twice a month — almost always the 1st through the 15th and the 16th through the last day of the month. That's 24 paychecks a year. Because the two halves of a month have different numbers of working days, your hours change from period to period, so you total your actual daily hours rather than assuming a fixed number.
(10 × 8) + 4 = 84 hours for the period. At $20/hr straight time that's $1,680 gross — before any overtime owed on weeks you topped 40 hours.
The overtime gotcha (this is the important part)
Overtime under the FLSA is based on the workweek — hours over 40 in a fixed 7-day week — not the pay period. A semi-monthly period almost never lines up with whole workweeks: the 1st–15th can contain parts of three different workweeks. So you cannot just take everything over 80 hours for the half-month and call it overtime. You have to split the period back into its workweeks, apply the 40-hour rule to each one, then add it up. Getting this wrong is the single most common semi-monthly payroll error.
Semi-monthly vs. bi-weekly
| Semi-monthly | Bi-weekly | |
|---|---|---|
| Paychecks / year | 24 | 26 |
| Pay dates | Fixed dates (e.g. 15th & 30th) | Same weekday, every 2 weeks |
| Lines up with workweek? | No | Yes |
| Overtime math | Harder (split into weeks) | Straightforward |
Frequently asked questions
What is a semi-monthly pay period?
Paid twice a month — typically the 1st–15th and 16th–end of month, 24 paychecks a year. Different from bi-weekly (every two weeks, 26 paychecks).
How do I calculate overtime on a semi-monthly timesheet?
Per workweek, not per period. Split the half-month back into its 7-day workweeks, apply the 40-hour rule to each, then total. You can't just take hours over 80.
How many hours are in a semi-monthly pay period?
A full-time period averages ~86.67 hours (2,080 ÷ 24), but actual hours vary by how many workdays fall in that half of the month.
Is semi-monthly the same as bi-weekly?
No — semi-monthly is twice a month on fixed dates (24/yr); bi-weekly is every two weeks on a fixed weekday (26/yr).
Is it free?
Yes — free, no sign-up, runs entirely in your browser. Nothing is stored or sent anywhere.