How to calculate worked hours properly

Adding up hours is easy. Breaks, midnight and rounding are where timesheets and payroll disagree.

Shifts that cross midnight

A shift from 22:00 to 06:00 is eight hours. Subtract the numbers and you get minus sixteen, which is what a spreadsheet will tell you unless someone thought about it.

The rule is simple: if the end time is earlier than the start, the shift crossed midnight, so add a day before subtracting. Every night worker meets this and a surprising number of timesheets get it wrong.

Breaks, paid and unpaid

Whether a break is paid is a matter of contract and law, not arithmetic, and it varies by country. What matters for the calculation is being explicit: record the break, and know whether you are subtracting it.

A rest break of a few minutes is usually paid. A meal break where you are free to leave usually is not. If you are being paid for a break, do not deduct it — and if you are not, deducting it is what makes your total match the payslip.

Rounding, which is where the disagreements are

Employers often round clock times to a convenient interval — six minutes (a tenth of an hour), or fifteen.

Rounding to the nearest interval is fair, because it evens out: sometimes you gain three minutes, sometimes you lose three.

Rounding always down is not. Clock in at 08:57 and out at 17:14, rounded down to quarter hours, and two minutes vanish every day. Over a year that is several hours worked and unpaid.

In the United States, rounding is permitted under the Fair Labor Standards Act provided it does not systematically favour the employer over time — which always-down rounding does by construction. Rules elsewhere differ, and the principle that you should be paid for hours worked does not.

This is worth checking rather than assuming. Calculate your hours unrounded, then with your employer's convention, and see whether the difference is neutral or always in one direction.

Overtime thresholds

Whether overtime is counted per day or per week, and at what multiplier, depends on your jurisdiction and contract. Forty hours a week at one and a half times is common in the United States; many other countries count differently or not at all.

Keep the record yourself

Not out of suspicion — because a payslip that does not match is much easier to query when you can say which day it was. Note the times as they happen rather than reconstructing the week on Friday, when everyone rounds to the times they meant to work.

Frequently asked questions

How do I calculate a shift that goes past midnight?

Add a day to the end time before subtracting. A shift from 22:00 to 06:00 is eight hours, not minus sixteen.

Should I subtract my lunch break?

If it is unpaid, yes — that is what makes your total match the payslip. Short rest breaks are usually paid and should not be deducted. It depends on your contract and local law.

Is it legal for an employer to round my hours?

Rounding is generally permitted provided it does not consistently favour the employer. Rounding to the nearest interval evens out; rounding always down does not, and takes minutes you worked.

What is a tenth of an hour?

Six minutes. Payroll systems often work in tenths, which is why rounding to six-minute intervals is common.

How do I convert hours and minutes to decimal?

Divide the minutes by 60. Seven hours and 45 minutes is 7.75 hours, which is the form most payroll systems want.