How do I calculate hours worked?

Subtract the start time from the end time to get the elapsed span, then subtract any unpaid break. The result is your worked time. A 9:00 AM to 5:30 PM shift with a 30-minute unpaid lunch is 8h 30m minus 30m, so 8 hours.

How do I subtract lunch from work hours?

Enter the unpaid lunch in minutes and deduct it from that shift's elapsed time before totalling. Only unpaid breaks come off — a paid lunch stays in the total. The Work Hours Calculator and Time Card Calculator do this per shift automatically.

How do I calculate overnight hours?

When the end time is not later than the start time, the shift crosses midnight. Add 24 hours to the difference: 22:00 to 06:00 is (06:00 − 22:00) + 24h = 8 hours. The Shift Calculator detects this and labels the shift overnight.

Is 7 hours 30 minutes equal to 7.5 hours?

Yes. 30 minutes is half of 60, so it is 0.50 of an hour, giving 7 + 0.50 = 7.50 decimal hours. It is not 7.30 — that would be only 18 minutes past the hour.

How do I calculate weekly work hours?

Work out each day's hours separately, then add them together. Convert each day to decimal hours first if your system needs decimals. The Timesheet Calculator totals weekly and biweekly entries, and the Time Card Calculator does the same from clock times with overtime.

Work & Hours

How to Calculate Work Hours Correctly

Working out hours worked comes down to one formula, but the details — breaks, overnight shifts and decimal hours — are where most mistakes happen. This guide walks through the maths step by step, with worked examples, and points you to the right calculator for each job.

The basic formula

Hours worked is the elapsed time on the clock, minus any time you were not paid for:

Hours Worked = End Time − Start Time − Unpaid Break

Subtract the start time from the end time to get the elapsed span of the shift, then subtract any unpaid break. The result is the time you were actually working and getting paid for.

A worked example

Take a shift from 9:00 AM to 5:30 PM with a 30-minute unpaid lunch.

Elapsed time: 5:30 PM − 9:00 AM = 8 hours 30 minutes.
Subtract the unpaid break: 8h 30m − 30m = 8 hours.
Decimal hours: 8.00.

So that shift is 8 hours of worked time. The 30-minute lunch came off the total because it was unpaid. The Work Hours Calculator does both steps for every shift you enter and totals them.

Paid vs unpaid breaks

Only unpaid time should come off the total. If your lunch is paid, leave the break at zero — the elapsed time already includes it. If your lunch is unpaid, enter it in minutes and it is deducted from that shift before the day or week total is summed.

A common slip is subtracting a break that was already paid, which undercounts the shift. If you are not sure whether a break is paid, check your contract or employer's policy before deducting it.

Overnight shifts

When a shift crosses midnight, the end time is earlier than the start time on the clock. A 22:00 to 06:00 shift would look like a negative number if you just subtracted. The fix is to add 24 hours when the end is not later than the start:

If End ≤ Start: Elapsed = (End − Start) + 24 hours

So 22:00 to 06:00 is (06:00 − 22:00) + 24h = −16h + 24h = 8 hours. The Shift Calculator and Work Hours Calculator both detect overnight shifts automatically and label them.

Hours and minutes vs decimal hours

Timesheet and payroll systems usually store time as decimal hours, where minutes are a fraction of an hour rather than a separate number. To convert, divide the minutes by 60 and add them to the hours:

Decimal Hours = Hours + (Minutes ÷ 60)

7 hours 45 minutes = 7 + 45 ÷ 60 = 7.75 decimal hours. It is not 7.45 — that would mean 7 hours and 45 hundredths of an hour, which is only 27 minutes. See our Decimal Hours Explained guide for the full breakdown, or use the Decimal Hours Calculator to convert either way.

Calculating weekly work hours

To total a week, calculate each day's worked time and add the results together. Convert each day to decimal hours first if your system needs decimals, then sum the decimals — adding hours-and-minutes columns by hand is where carrying errors creep in.

For example, a week of 8h, 7h 30m, 8h, 7h 45m and 8h totals 39h 15m, or 39.25 decimal hours. The Timesheet Calculator handles weekly and biweekly totals with per-day entry, and the Time Card Calculator does the same from clock-in and clock-out times with overtime split out. For the full step-by-step workflow — breaks, decimal conversion, weekly totals, overtime and rounding — see Timesheet Hours & Payroll Calculations Explained, and for overtime pay specifically see Overtime Hours Explained.

Common mistakes

Subtracting a paid break. Only unpaid time comes off the total. Deducting a paid lunch undercounts the shift.
Writing 7.30 for 7h 30m. Decimal hours use base 10, so 30 minutes is 0.50, not 0.30. The correct value is 7.50.
Forgetting overnight shifts wrap past midnight. A 22:00–06:00 shift is 8 hours, not −16. Add 24 hours when end ≤ start.
Adding hours and minutes as if they were decimals. 1h 50m + 0h 20m is 2h 10m, not 1.70. Carry minutes at 60, not 100.
Rounding each entry before totalling. Convert and total first, then round the final sum. Rounding every row drifts the week's total.
Letting a break exceed the shift go negative. If a break is longer than the shift, the shift is zero, not a negative number.

Which calculator should I use?

The right tool depends on what you are totalling:

Work Hours Calculator — one or more shifts from start/end times with breaks, totalled into a day or week.
Shift Calculator — a single shift's length, break and worked hours, with optional pay.
Time Card Calculator — a full Monday–Sunday week from clock-in/out times, with regular vs overtime and pay.
Timesheet Calculator — weekly or biweekly totals from per-day hours, with per-week overtime.
Lunch Break Calculator — break duration, return time, or worked hours after an unpaid lunch.
Overtime Calculator — regular vs overtime hours and pay from a total and a rate.

FAQs

How do I calculate hours worked?: Subtract the start time from the end time to get the elapsed span, then subtract any unpaid break. The result is your worked time. A 9:00 AM to 5:30 PM shift with a 30-minute unpaid lunch is 8h 30m minus 30m, so 8 hours.
How do I subtract lunch from work hours?: Enter the unpaid lunch in minutes and deduct it from that shift's elapsed time before totalling. Only unpaid breaks come off — a paid lunch stays in the total. The Work Hours Calculator and Time Card Calculator do this per shift automatically.
How do I calculate overnight hours?: When the end time is not later than the start time, the shift crosses midnight. Add 24 hours to the difference: 22:00 to 06:00 is (06:00 − 22:00) + 24h = 8 hours. The Shift Calculator detects this and labels the shift overnight.
Is 7 hours 30 minutes equal to 7.5 hours?: Yes. 30 minutes is half of 60, so it is 0.50 of an hour, giving 7 + 0.50 = 7.50 decimal hours. It is not 7.30 — that would be only 18 minutes past the hour.
How do I calculate weekly work hours?: Work out each day's hours separately, then add them together. Convert each day to decimal hours first if your system needs decimals. The Timesheet Calculator totals weekly and biweekly entries, and the Time Card Calculator does the same from clock times with overtime.