What this calculates
Enter a start and end time on the 12-hour clock and any unpaid break, and this gives the time between them in hours and minutes, in decimal hours for a timesheet, and in minutes. An end time earlier than the start is read as the next day, so night shifts work too.
The formula
Minutes after midnight
(hour on the 24-hour clock) × 60 + minutesDuration
end − start − break, adding 1,440 minutes when the end is the next day
Decimal hours
minutes ÷ 60On the 12-hour clock, 12 am is midnight (0 minutes) and 12 pm is noon (720 minutes); for any other pm time, add 12 to the hour.
Worked example
A night shift from 10 pm to 6 am is 360 + 1,440 − 1,320 = 480 minutes, also 8 hours. From 9:00 am to 4:45 pm is 7 h 45 min, which is 7.75 decimal hours.
When to use it, and the mistakes to avoid
Use it to fill in a timesheet, check your pay for hourly work, add up study or practice time, or find out how long a journey, meeting or event lasted.
The mistakes that cost the most:
- Writing minutes as a decimal. 7 hours 45 minutes is 7.75 hours, not 7.45 — paying at 7.45 loses 18 minutes.
- Getting a negative answer overnight. 10 pm to 6 am is not −16 hours; the end is the next day, so it is 8 hours.
- Mixing up 12 am and 12 pm. 12 pm is noon; 12 am is midnight.
- Forgetting the unpaid break. A 9-to-5:30 day with a 30-minute lunch is 8 paid hours, not 8.5.
- Adding times like decimals. 1:50 plus 0:20 is 2 h 10 min, not 1.70.
FAQ
How do I calculate the hours between two times?
Turn both into minutes after midnight, subtract, and divide by 60. 9:00 am is 540 minutes and 5:30 pm is 1,050, so the span is 510 minutes: 8 hours 30 minutes, or 8.5 hours.
How do I calculate hours for a night shift?
When the end time is earlier than the start, it is the next day, so add 24 hours (1,440 minutes) to the end. 10 pm to 6 am is 360 + 1,440 − 1,320 = 480 minutes, which is 8 hours.
What are decimal hours?
Hours written as a single decimal number, which is what payroll multiplies by an hourly rate. Divide the minutes by 60: 7 hours 45 minutes is 7.75 hours, not 7.45. 15 minutes is 0.25, 30 minutes 0.5, and 45 minutes 0.75.
Should I take the lunch break off?
Take it off if it is unpaid, which is the usual case. A 9 am to 5:30 pm day with a 30-minute unpaid lunch is 8 hours of paid time.
Is 12 pm noon or midnight?
12 pm is noon and 12 am is midnight. So 12 am to 12 pm is the 12 hours from midnight to noon.
What if the start and end are the same time?
The calculator reads that as no time passing. A full 24-hour shift also ends on the same clock time; its answer is simply 24 hours.