How to use the hours calculator
- Enter the start time and the end time. For a shift that ends after midnight, just enter the real end time, such as 6:00 AM. When the end is earlier than the start, the calculator counts it as the next day.
- Add an unpaid break if you had one, in minutes. For a half-hour lunch, enter 30; for an hour, enter 60. Leave it empty if your breaks are paid.
- Read the answer three ways: hours and minutes (8:30), decimal hours (8.50) and total minutes (510).
The answer updates as you type. The Common shifts buttons fill in a typical day in one tap, and Copy result copies the times and the answer so you can paste them into a message, a timesheet or a spreadsheet.
To add up a whole week of shifts, with overtime, use the time card calculator.
Hours for common shifts
These are the hours between some common start and end times, with no break, a 30-minute lunch and a one-hour lunch. Decimal hours are in parentheses.
| Shift | No break | 30 min lunch | 1 hour lunch |
|---|---|---|---|
| 9:00 AM to 5:00 PM | 8:00 (8.00) | 7:30 (7.50) | 7:00 (7.00) |
| 8:00 AM to 5:00 PM | 9:00 (9.00) | 8:30 (8.50) | 8:00 (8.00) |
| 8:30 AM to 5:00 PM | 8:30 (8.50) | 8:00 (8.00) | 7:30 (7.50) |
| 7:00 AM to 3:30 PM | 8:30 (8.50) | 8:00 (8.00) | 7:30 (7.50) |
| 6:00 AM to 2:30 PM | 8:30 (8.50) | 8:00 (8.00) | 7:30 (7.50) |
| 7:00 AM to 7:00 PM | 12:00 (12.00) | 11:30 (11.50) | 11:00 (11.00) |
| 10:00 PM to 6:00 AM (overnight) | 8:00 (8.00) | 7:30 (7.50) | 7:00 (7.00) |
So 8am to 5pm is 9 hours, or 8 hours 30 minutes with a half-hour lunch, and 8 hours with a one-hour lunch. 9 to 5 is 8 hours, or 7.5 hours with a half-hour lunch. Five days of 8am to 5pm with a one-hour lunch is a 40-hour week.
How the hours are worked out
The calculator turns both times into minutes after midnight, takes the start from the end, then takes off the break:
hours worked = (end time minus start time) minus unpaid break
For 7:00 AM to 3:30 PM with a 30-minute lunch:
| Step | Minutes |
|---|---|
| End: 3:30 PM is 15:30, so 15 x 60 + 30 | 930 |
| Start: 7:00 AM is 7 x 60 | 420 |
| End minus start | 510 |
| Less the 30-minute lunch | 480 |
| Hours worked: 480 divided by 60 | 8:00 (8.00) |
If the end time is earlier than the start time, 24 hours (1,440 minutes) is added to the end first. That is how 10:00 PM to 6:00 AM comes out as 8 hours and not as a negative number.
Hours and minutes or decimal hours
8:30 and 8.30 are not the same. 8:30 means 8 hours and 30 minutes. In decimal hours that is 8.50, because 30 minutes is half an hour. Payroll and invoicing software usually wants decimal hours, so the calculator shows both.
To turn minutes into a decimal part of an hour, divide by 60: 15 minutes is 0.25, 45 minutes is 0.75 and 20 minutes is 0.333..., shown as 0.33. For the full list from 1 to 60 minutes, see the time to decimal chart.
Which breaks to take off
Only take off breaks you are not paid for. Under the US federal rules, a real meal break is not work time when you are "completely relieved from duty", and "ordinarily 30 minutes or more is long enough" for one. If you have to eat at your desk or stay at your machine, that time counts as work.
Short breaks are different. The same rules say rest periods "running from 5 minutes to about 20 minutes" are "customarily paid for as working time" and must be counted as hours worked. So do not take off a 10-minute coffee break.
The Department of Labor also notes that "federal law does not require lunch or coffee breaks." States can have their own break laws, and your employer's policy decides which breaks are paid on top of that. If you are not sure, ask how your breaks are recorded.
Night shifts and other cases
- Overnight: a shift is counted from its start to its end, even across midnight. The result shows a note when it runs into the next day.
- Same start and end: if both times are the same, the calculator asks you to check them, because it cannot tell zero hours from a full 24.
- Break too long: a break longer than the time between start and end is flagged, not counted.
- Clock changes: on the night the clocks go forward or back for daylight saving time, a shift that runs across the hour the clocks change (2:00 AM in the US, 1:00 AM in spring and 2:00 AM in autumn in the UK) is really one hour shorter or longer than the clock times suggest. Add or take off that hour yourself.
Questions and answers
How many hours is 8am to 5pm?
9 hours. With a 30-minute unpaid lunch it is 8 hours 30 minutes (8.50 decimal hours), and with a one-hour lunch it is 8 hours.
How many hours is 9 to 5?
8 hours. With a 30-minute unpaid lunch it is 7 hours 30 minutes, which is 7.50 in decimal hours.
How many hours is 7am to 3:30pm?
8 hours 30 minutes. With a 30-minute unpaid lunch it is exactly 8 hours.
How do I work out hours for a night shift?
Enter the start and the real end time, such as 10:00 PM and 6:00 AM. Because the end is earlier than the start, the calculator counts it as the next morning: 8 hours, or 7 hours 30 minutes with a 30-minute break.
Is 8.30 hours the same as 8 hours 30 minutes?
No. 8 hours 30 minutes is 8.50 decimal hours. 8.30 decimal hours is 8 hours 18 minutes, because 0.30 of an hour is 18 minutes.
Should I take my lunch break off my hours?
Only if it is unpaid. A meal break where you are fully relieved from work, usually 30 minutes or more, is normally unpaid. Short breaks of about 5 to 20 minutes are normally paid work time under the federal rules.
Sources
Checked on 7 October 2026. If a rule has changed, please tell us.