Minutes are sixtieths of an hour, not hundredths. Every problem in this article follows from that one fact, and so does every quiet underpayment it causes.
How do you convert minutes to decimal hours?
Divide the minutes by 60. That gives you the fraction of an hour, which you add to the whole hours.
The working
30 minutes ÷ 60 = 0.5 → 7h 30m = 7.5 hours 15 minutes ÷ 60 = 0.25 → 7h 15m = 7.25 hours 20 minutes ÷ 60 = 0.333… → 7h 20m = 7.33 hours 45 minutes ÷ 60 = 0.75 → 7h 45m = 7.75 hours
Writing 7.30 on a timesheet does not mean seven hours thirty minutes. It means seven and three-tenths of an hour — seven hours and eighteen minutes. You have just given away twelve minutes.
Minutes to decimal conversion table
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 5 | 0.08 | 35 | 0.58 |
| 10 | 0.17 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 25 | 0.42 | 55 | 0.92 |
| 30 | 0.50 | 60 | 1.00 |
Only 15, 30 and 45 land on clean decimals. Everything else recurs, which is why a rounded timesheet drifts if you round each day instead of totalling the minutes first and converting once at the end.
How do you calculate hours worked in a day?
- Take the start time from the finish time09:00 to 17:30 is 8 hours 30 minutes. If it helps, count to the next whole hour and then on to the finish, rather than trying to subtract the clock readings directly.
- Handle a night shift by rolling over midnightA finish time that looks earlier than the start has crossed midnight. 22:00 to 06:00 is 8 hours: two hours to midnight, six after it. Subtracting the clock numbers gives minus sixteen, which is the classic wrong answer.
- Subtract the unpaid breakIn minutes, from the total. 8 hours 30 minutes less a 30-minute lunch is 8 hours. If the break is paid, do not subtract it.
- Convert once, at the endTotal the whole week in hours and minutes first, then divide the minutes by 60. Converting and rounding each day separately lets small errors accumulate across five or six rows.
Why does a 9-to-5 come to 37.5 hours?
Because of the lunch break. Nine to five is eight hours on the clock, but most UK salaried contracts treat lunch as unpaid, so each day is really seven and a half.
The working
Per day: 09:00 → 17:00 = 8h, less 30m unpaid = 7h 30m Per week: 7h 30m × 5 = 37h 30m Decimal: 37h 30m = 37.5 hours
That is where the 37.5-hour week in so many contracts comes from. A contract written as 40 hours usually means the break is paid, or the day is longer than eight hours.
Common questions
What is 1 hour 45 minutes in decimal?
1.75 hours. 45 ÷ 60 = 0.75, added to the 1 whole hour. The other quarter-hours are 0.25 for 15 minutes and 0.5 for 30.
What is 20 minutes as a decimal?
0.33 recurring — 20 ÷ 60 = 0.3333… Most payroll systems take two decimal places, so 0.33. Over a long timesheet that rounding is worth watching: twenty rows each rounded down by a third of a minute is nearly seven minutes gone.
How do I add up hours and minutes?
Add the hours and the minutes separately, then carry any minutes over 60 into the hours column. 7h 45m plus 6h 30m is 13h 75m, and 75 minutes is 1h 15m, so the answer is 14h 15m. Doing it in decimal instead avoids the carry entirely, which is one reason payroll prefers it.
Should I round my hours?
Total in exact minutes and convert once at the end. If your employer rounds to the nearest quarter-hour, that is a policy applied to the final figure — it should never be applied to each day and then summed, because the errors compound in whoever’s favour the rounding rule happens to lean.
Does this work out my pay after tax?
No. Hours multiplied by a rate gives gross pay. What actually reaches your account depends on your tax code, National Insurance, pension contributions and any student loan plan — all of which change every April, and none of which are guessed at here.
What this does not cover
- Overtime rates. Every hour above is paid the same; time-and-a-half, double time and unsocial-hours premiums have to be worked out separately.
- Tax and National Insurance. Any pay figure is gross.
- Holiday accrual, sick pay and pension contributions.
- Whether the breaks you are getting are the ones you are entitled to. That is a question about your contract and about working time rules, not about arithmetic.
Check this before you rely on it. A free guide to everyday arithmetic — not tax, accounting, financial, legal or medical advice. The working is shown above so you can verify it against your own figures. See our terms of use.