How hours worked are calculated
The calculator measures the time from your start time to your end time, then subtracts any break. If the end time is earlier than the start time, it assumes the shift runs through midnight and adds 24 hours, so night workers get the right answer without any extra fiddling. The result appears twice: as hours and minutes (8:30), which is how people talk about shifts, and as decimal hours (8.5), which is how payroll systems and timesheets want it. The two look similar but mean different things: 8:30 is eight and a half hours, while a careless "8.30" typed into a timesheet would underpay you by 12 minutes. Typical uses include checking a payslip against a rota, filling in agency timesheets, invoicing clients for time on site, and totting up flexi-time at the end of the month.
Worked examples
Overnight shifts
A shift from 22:00 to 06:00 confuses plenty of calculators, because subtracting the times gives minus 16 hours. This one spots that the end time is before the start time and treats it as the next day, showing the shift length with an overnight label so you can confirm that is what you meant. If you work nights regularly it is worth knowing the rules: under the Working Time Regulations, night workers should not average more than 8 hours of work in each 24-hour period, and employers must offer a free health assessment. Night premiums are a matter of contract rather than law, so a higher hourly rate is common but not automatic.
Breaks, pay and timesheets
UK workers over 18 have a legal right to an uninterrupted 20-minute rest break on any shift longer than 6 hours, and that break is unpaid unless your contract says otherwise. That is why timesheets ask for break minutes separately: an 8:30 shift with a half-hour unpaid lunch pays for 8 hours, not 8 and a half. To turn hours into money, multiply decimal hours by your hourly rate. Working 8 hours a day, 5 days a week is 40 hours, and at £13.50 an hour that is £540 a week before tax. To see what a regular weekly pattern means as an annual salary, the hourly wage to salary converter does that sum in one step. One caveat: some clock-in systems round times to the nearest 5, 6 or 15 minutes, so the odd minute of difference between this calculator and a payslip is usually rounding rather than an error. If the gap is bigger than that, query it, because unpaid minutes at the start and end of shifts add up over a year.
Frequently asked questions
How does the calculator handle overnight shifts?
If the end time is earlier than the start time, the calculator assumes the shift crosses midnight and adds 24 hours. So 22:00 to 06:00 counts as 8 hours, not minus 16. The shift length row is labelled overnight so you can see this has happened.
Why does 7 hours 30 minutes show as 7.5 hours?
Decimal hours express the minutes as a fraction of an hour, so 30 minutes is 0.5 hours, not 0.30. Payroll systems use decimal hours because pay is hours multiplied by an hourly rate, and that multiplication only works with decimals.
Are breaks paid in the UK?
Workers over 18 are entitled to an uninterrupted 20-minute rest break when working more than 6 hours, and by default it is unpaid. Many employers offer longer or paid breaks in the contract, so check yours before deciding what to subtract.
How do I add up a whole week of shifts?
Work out each shift here, note the hours and minutes, then add them together with the time calculator. Keeping everything in hours and minutes until the final total avoids decimal rounding creeping in.
Is anything I enter stored?
No. The calculation runs entirely in your browser and nothing is sent to any server. Refreshing the page resets the times.