Hours Calculator
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- Formula shown
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Results
9:00 AM to 5:30 PM minus a 30-minute break is 8 hours, or 8.00 decimal hours
How to use the hours calculator
- Enter the start time and the end time. Your device shows its usual clock picker, 12-hour or 24-hour.
- Enter the total unpaid break in minutes, or leave it at 0.
- Read the hours as h:mm and as decimal hours. If the end time is earlier than the start, the calculator treats it as the next day.
For a full week of shifts with overtime and pay, use the time card calculator instead.
Hours worked formula
Hours worked = span − unpaid break
Decimal hours = hours + minutes ÷ 60 (rounded to 2 places)
Both times are first turned into minutes after midnight, so 9:45 PM becomes 21 × 60 + 45 = 1,305. If the end is smaller than the start, the shift has crossed midnight and 1,440 minutes (24 hours) are added to the end. Subtracting the break gives the paid time, which is shown as hours and minutes and as decimal hours, the format most payroll and invoicing software uses.
Worked example: a night shift
A shift runs from 9:45 PM to 6:15 AM with a 45-minute unpaid break. In minutes after midnight that is 1,305 to 375. Because 375 is smaller, add 1,440 to get 1,815; 1,815 − 1,305 = 510 minutes, or 8:30. Taking off the break leaves 465 minutes: 7:45, which is 7.75 decimal hours.
Minutes to decimal hours
Decimal hours are minutes divided by 60. Six-minute steps give exact tenths, which is why some employers record time in tenths of an hour.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.08 | 25 | 0.42 |
| 6 | 0.10 | 30 | 0.50 |
| 10 | 0.17 | 36 | 0.60 |
| 12 | 0.20 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 18 | 0.30 | 48 | 0.80 |
| 20 | 0.33 | 50 | 0.83 |
| 24 | 0.40 | 55 | 0.92 |
Common shift lengths
| Shift | Unpaid break | Hours (h:mm) | Decimal |
|---|---|---|---|
| 9:00 AM – 5:00 PM | 0 min | 8:00 | 8.00 |
| 9:00 AM – 5:30 PM | 30 min | 8:00 | 8.00 |
| 8:00 AM – 4:30 PM | 30 min | 8:00 | 8.00 |
| 7:00 AM – 3:30 PM | 30 min | 8:00 | 8.00 |
| 6:00 AM – 6:00 PM | 60 min | 11:00 | 11.00 |
| 2:00 PM – 10:30 PM | 30 min | 8:00 | 8.00 |
| 10:00 PM – 6:00 AM (overnight) | 30 min | 7:30 | 7.50 |
| 7:00 PM – 7:00 AM (overnight) | 60 min | 11:00 | 11.00 |
Tips for accurate timesheets
- Write the format down. 7:45 (hours and minutes) is 7.75 decimal hours. Entering 7.45 into a decimal field under-pays by 18 minutes.
- Round only at the end. Rounding each day's decimal hours and then adding can drift by a few hundredths over a week; total the minutes first.
- Shifts over 24 hours can't be described by two clock times alone. Use the time duration calculator with dates.
- Daylight saving nights are an hour shorter or longer than the clock suggests. On those dates, add or subtract the hour by hand.
- Break rules vary. Whether a break is paid depends on your contract and local law; subtract only the breaks that are unpaid.
To add up lengths of time or find when something ends, see the time calculator.
Frequently asked questions
How do I calculate hours worked?
Subtract the start time from the end time, then subtract unpaid breaks. 9:00 AM to 5:30 PM is 8 hours 30 minutes; take off a 30-minute lunch and you have 8 hours, or 8.00 decimal hours.
How do I calculate hours for an overnight shift?
When the end time is earlier than the start time, the shift ends the next day, so add 24 hours to the end before subtracting. 9:45 PM to 6:15 AM is 8 hours 30 minutes; with a 45-minute break that is 7 hours 45 minutes, or 7.75 decimal hours. The calculator does this automatically.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours. 3 hours 50 minutes is 3 + 50 ÷ 60 = 3.83 hours (rounded to two decimals). Common values: 15 minutes = 0.25, 30 minutes = 0.5, 45 minutes = 0.75.
Is 8:30 the same as 8.30 hours?
No. 8:30 means 8 hours 30 minutes, which is 8.5 decimal hours. 8.30 decimal hours is 8 hours and 18 minutes (0.30 × 60). Mixing the two is one of the most common timesheet errors, so check which format your payroll system expects.
Should I subtract my lunch break?
Subtract only unpaid breaks. Under US federal rules, short rest breaks (usually 20 minutes or less) count as paid work time, while a genuine meal period of 30 minutes or more, when you are fully relieved of duties, usually does not. Rules differ by state and country, so check with your employer or labour authority.