Timesheet Calculator
Add up hours worked from clock-in and clock-out times, with breaks and optional pay, handling overnight shifts and the rounding rules employers use.
total hours
Rounding to nearest is nearly free. Rounding one way is not.
Most timesheet policies round each shift to a fixed unit. Simulating 250 shifts of about eight hours, ragged by a few minutes either way, and billing each under three rules:
| Rounded to | Rule | Drift over the year | At $25/hour |
|---|---|---|---|
| 6 min | to nearest | +2.10 h | +$53 |
| 6 min | always down | -10.80 h | −$270 |
| 6 min | always up | +11.10 h | +$278 |
| 15 min | to nearest | -0.75 h | −$19 |
| 15 min | always down | -30.00 h | −$750 |
| 15 min | always up | +29.75 h | +$744 |
| 30 min | to nearest | +0.50 h | +$13 |
| 30 min | always down | -60.50 h | −$1513 |
| 30 min | always up | +59.00 h | +$1475 |
Rounding to nearest is very nearly free — 0.75 hours over a whole year at 15 minutes — because the errors cancel. That is the entire point of rounding to nearest, and it holds up under measurement.
Rounding in a fixed direction does not cancel. It accumulates at roughly half the rounding unit every shift, forever. Always rounding down to the nearest quarter hour costs 30 hours a year — most of a working week, or about $750 at $25 an hour, transferred by a rule that reads as pure administration.
The size of the unit matters as much as the direction. At 30-minute rounding, always-down reaches 61 hours; at 6 minutes it is 11. The worst any single shift can lose is half a unit under round-to-nearest, against almost a whole unit under always-down: 3 vs 5 minutes at 6, 7.5 vs 14 minutes at 15, 15 vs 29 minutes at 30.
And only a third of minute values are exact in decimal hours
Timesheets are kept in hours and minutes and paid in decimal hours, and that conversion is not clean either. m minutes is m ÷ 60 hours, which lands on exactly two decimal places only when m is a multiple of three:
| Minutes | Decimal hours | Exact to 2dp |
|---|---|---|
| :15 | 0.25 | yes |
| :20 | 0.333333 | no — recurring |
| :30 | 0.5 | yes |
| :45 | 0.75 | yes |
| :50 | 0.833333 | no — recurring |
20 of the 60 minute values are exact and the other 40 are repeating decimals that get rounded somewhere. Individually that is a fraction of a penny and not worth anyone's attention.
It is worth knowing because of how it interacts with the section above. A system that truncates rather than rounds at this step adds a second small, one-directional loss on top of whatever the time rounding already did — and two independent downward biases in the same pipeline is how a payroll figure ends up quietly and consistently short.
If you are choosing a policy rather than living with one: round to nearest, use the smallest unit anyone will tolerate, and keep minutes as whole numbers until the final conversion to decimal hours. All three are free to implement and the difference over a year is measured in days.
How to use
- Enter each day's start and end times.
- Deduct unpaid breaks.
- Add your hourly rate for a pay total.
- Check overnight shifts are counted correctly.
Frequently asked questions
How are overnight shifts handled?
By recognising that an end time earlier than the start time means the shift crossed midnight, and adding a day accordingly. Handling this wrongly produces a negative or wildly short shift, which is the classic timesheet bug.
Should I use decimal hours or hours and minutes?
Payroll almost always works in decimal hours, where 7 hours 30 minutes is 7.5. The conversion trips people up because 7.30 is not 7 hours 30 minutes — it is 7 hours 18. That misreading is a common source of pay disputes.
Is rounding time legal?
In the US, rounding to increments of up to 15 minutes has been permitted provided it does not systematically favour the employer over time. Rounding that consistently shortens paid time is unlawful, and rules differ by jurisdiction, so local guidance governs.
Are breaks paid?
It depends on length and jurisdiction. Under US federal rules, short breaks of around 20 minutes or less are generally counted as paid working time, while genuine meal breaks during which you are fully relieved of duty are generally not. State rules add further requirements.
How is overtime calculated?
Usually at 1.5 times the regular rate beyond 40 hours in a week under US federal law, though some states add daily thresholds. What counts toward the total, and whether bonuses affect the regular rate, is more involved than it first appears.
Is this a legal record?
No. It is a calculator for checking your own figures, not a system of record. Where hours are disputed, contemporaneous records and your employer's official system are what matter, and employment law questions need proper advice.
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