Time duration is the end time minus the start time, minus any break
If you start at 9:00 AM and finish at 6:00 PM, the two times are 9 hours apart. Subtract a 1-hour lunch and the time actually worked is 8 hours (480 minutes, 8.00 decimal hours). A night shift from 10:30 PM to 6:15 AM crosses midnight, so you add 24 hours and get 7 hours 45 minutes. After a 30-minute break, that is 7 hours 15 minutes (7.25 hours).
Enter a start time and an end time in the calculator above and it does this for you. If the end time is earlier than the start time, it is counted as the next day, and the break can be entered in minutes or as hours:minutes. The result shows the actual time after the break, the total time, and the total minutes and decimal hours that are easy to copy into a timesheet. The 24-hour clock below shows which part of the day the span covers, and you can drag the dots on it to change the times.
Three mistakes people make when subtracting by hand
Time is counted in 60s, not 10s, so subtracting the digits the way you would subtract ordinary numbers often goes wrong.
- Borrowing in the minutes: for 1:10 PM to 2:05 PM, subtracting 110 from 205 gives 95, which looks like 95 minutes. You have to borrow an hour (60 minutes) in the minutes place, so the answer is 55 minutes.
- Crossing midnight: on a 24-hour clock, subtracting 22:30 (10:30 PM) from 06:15 (6:15 AM) gives a negative 16 hours 15 minutes. Because the end is on the next day, you add 24 hours and count 7 hours 45 minutes.
- Turning minutes into a decimal: writing 7 hours 20 minutes as 7.2 hours is really 7 hours 12 minutes. 20 minutes is 20 ÷ 60 = 0.33 hours, so the correct value is 7.33, and writing 7.2 loses 8 minutes a day.
That is why a calculator is safer whenever you need an exact "hours and minutes" figure: logging work or part-time hours, night and rotating shifts, study or workout time, or the length of a meeting, class or presentation.
How the calculation works
- Turn each time into time elapsed since midnight: 9:00 AM is 540 minutes after midnight and 6:00 PM is 1,080 minutes after. A minute is 60 seconds, an hour is 3,600 seconds, and a day is 86,400 seconds.
- Total time = end time − start time. If the end time is earlier than the start time, add 24 hours (1,440 minutes). If you set "Ends on" to "Next day", 24 hours is added even when the end time is the same or later, so a span from 9:00 AM to 10:00 AM the next day counts as 25 hours.
- Actual time = total time − break. If the break is longer than the total time, the calculator tells you instead of calculating.
- Total minutes = actual time ÷ 60 seconds, and decimal hours = actual time ÷ 3,600 seconds, rounded to two decimal places. 0.01 hour is 36 seconds.
Formula Actual time = (end time − start time, plus 24 hours if the end is earlier or "Next day" is selected) − break
Turn on "Include seconds" and the time fields gain seconds, the result adds total seconds, and total minutes show two decimal places. A task that starts at 8:59:40 AM and ends at 9:41:10 AM takes 41 minutes 30 seconds, or 41.5 minutes in total.
Minutes to decimal hours
These are the values to use when a timesheet or invoice asks for decimal hours. Each one is minutes ÷ 60, rounded to two decimal places.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 min | 0.08 | 35 min | 0.58 |
| 10 min | 0.17 | 40 min | 0.67 |
| 15 min | 0.25 | 45 min | 0.75 |
| 20 min | 0.33 | 50 min | 0.83 |
| 25 min | 0.42 | 55 min | 0.92 |
| 30 min | 0.50 | 60 min | 1.00 |
Worked examples
These values come from the same calculator. For a shift that crosses midnight, entering the end time alone is enough: it is counted as the next day.
| Situation | Start → End | Break | Total | Actual | Total minutes | Decimal hours |
|---|---|---|---|---|---|---|
| Regular workday | 9:00 AM → 6:00 PM | 60 min | 9 hours | 8 hours | 480 min | 8.00 |
| Early start | 8:30 AM → 5:45 PM | 60 min | 9 hours 15 minutes | 8 hours 15 minutes | 495 min | 8.25 |
| Night shift | 10:30 PM → 6:15 AM (next day) | 30 min | 7 hours 45 minutes | 7 hours 15 minutes | 435 min | 7.25 |
| Afternoon-to-overnight shift | 2:00 PM → 2:00 AM (next day) | 45 min | 12 hours | 11 hours 15 minutes | 675 min | 11.25 |
| Short meeting | 1:10 PM → 2:05 PM | 0 min | 55 minutes | 55 minutes | 55 min | 0.92 |
Which breaks to subtract: U.S. federal rules
Whether a break comes off your hours depends on what kind of break it is. The U.S. Department of Labor says: "Federal law does not require lunch or coffee breaks." The Fair Labor Standards Act (FLSA) does not require an employer to give breaks at all, but it does say how the time counts when breaks are given.
- Short rest breaks count as work time: when an employer offers short breaks, usually lasting about 5 to 20 minutes, federal law considers them compensable work hours. Leave these out of the break field.
- Meal periods usually do not: the Department of Labor describes meal periods, typically lasting at least 30 minutes, as time that is not work time and is not compensable. A 30-minute or 1-hour lunch you are free of work for is what you enter in the break field.
- State rules differ: some states set their own meal-break requirements, and the length and timing differ from state to state. Check your state labor office or the Department of Labor's state table for your state.
The calculator only subtracts the break you enter. It does not judge whether your break was long enough, or whether your meal period should be paid or unpaid. Those answers depend on federal and state law, your employer's policy and your actual duties during the break.
Common slip-ups
- Subtracting the break twice: if the clock-out time on your timesheet already has the break taken out, leave the break field at 0.
- Subtracting a paid rest break: a 10-minute coffee break that counts as work time should not go in the break field.
- 12 AM and 12 PM: 12:30 AM is 30 minutes after midnight (00:30), and 12:30 PM is half past noon.
- An exact 24-hour span: from 7:00 AM to 7:00 AM the next day, the start and end are the same, so the result is 0 minutes. Set "Ends on" to "Next day" to get 24 hours.
- Rounding decimal hours every day and adding them up: working 7 hours 20 minutes for three days is 22 hours, but adding 7.33 three times gives 21.99. When you combine several days, add the minutes first and convert to decimal hours at the end.
- Dropping the seconds: if your time clock records something like 6:00:59 PM, turn on "Include seconds" so the 59 seconds are not lost.
Limits and cautions
- The calculator handles one start and one end, and a span longer than a day only as far as "Next day". For a span over several days, use the Start Time & Elapsed Time Calculator. To add several spans, add them in minutes and convert to decimal hours only at the end.
- A browser time field works with a day that has no time changes (WHATWG HTML). In the United States, daylight saving time begins at 2:00 AM on the second Sunday of March, when the clocks skip ahead to 3:00 AM so that day has one less hour. It ends at 2:00 AM on the first Sunday of November, when the clocks go back to 1:00 AM so that day has an extra hour. On those nights the time that actually passed is 1 hour shorter or longer than the result here.
- Times from two different time zones, such as a departure and an arrival in local time, must be converted to one time zone before you enter them.
- Decimal hours are rounded to 0.01 hour (36 seconds). If your employer or organization records time in other units, such as tenths of an hour or 15-minute blocks, follow that rule.
- Pay, overtime and whether a break complied with the law are not calculated.
Sources
- 01U.S. Department of Labor: Breaks and Meal PeriodsFederal law does not require lunch or coffee breaks. Short breaks of about 5 to 20 minutes are compensable work hours. Meal periods, typically at least 30 minutes, are not work time
- 02U.S. Department of Labor: State Meal Period RequirementsTable of meal-period rules by state; requirements differ from state to state
- 03NIST: Daylight Saving TimeBegins at 2:00 a.m. on the second Sunday of March (one less hour that day), ends at 2:00 a.m. on the first Sunday of November (an extra hour that day)
- 04BIPM: The International System of Units (SI Brochure, 9th edition)Table 8: 1 min = 60 s, 1 h = 60 min = 3600 s, 1 d = 24 h = 86 400 s
- 05WHATWG HTML Living Standard: Time state (type=time)The default step of a time field is 60 seconds, and its value is the time elapsed since midnight on a day with no time changes
Frequently asked questions
How do I calculate the time between two times?
Subtract the start time from the end time, then subtract any break. From 9:00 AM to 6:00 PM is 9 hours, and after a 1-hour break the actual time is 8 hours (480 minutes, 8.00 hours). If the end time is earlier than the start time, it is treated as past midnight and 24 hours are added.
How do I enter a shift that crosses midnight?
Enter the start and end times as they are. When the end time is earlier than the start time, the calculator treats it as the next day and adds 24 hours. From 10:30 PM to 6:15 AM is 7 hours 45 minutes, and after a 30-minute break it is 7 hours 15 minutes.
Can it calculate spans longer than 24 hours?
Set "Ends on" to "Next day" and 24 hours are added even when the end time is the same or later, so 9:00 AM to 10:00 AM the next day is 25 hours. For a span of two days or more, use the Start Time & Elapsed Time Calculator, which takes dates as well.
How many decimal hours is 7 hours 20 minutes?
7.33 hours. 20 minutes is 20 ÷ 60 = 0.333… hours, which rounds to 0.33. Writing it as 7.2 hours would mean 7 hours 12 minutes and lose 8 minutes a day.
Which breaks should I subtract?
The U.S. Department of Labor says federal law does not require lunch or coffee breaks. Short breaks of about 5 to 20 minutes are compensable work hours, so leave them out of the break field. Meal periods, typically at least 30 minutes, are not work time. Some states set their own meal-break rules, so check your state. The calculator only subtracts what you enter and does not judge whether a break was legal.
Does it work with seconds?
Yes. Turn on "Include seconds" and the time fields gain seconds, and the result shows total seconds and total minutes to two decimal places. From 8:59:40 AM to 9:41:10 AM is 41 minutes 30 seconds, or 41.5 minutes.
What is the difference between Copy result and Copy link?
Copy result copies the start and end times, total time, break, actual time, total minutes and decimal hours as text, one per line. Copy link copies an address that holds the times and break you entered, so whoever opens it sees the same calculation.
What about daylight saving time?
The calculator assumes a day with no clock change. In the United States, daylight saving time begins at 2:00 AM on the second Sunday of March (one hour skipped) and ends at 2:00 AM on the first Sunday of November (one hour repeated), so on those nights the real time that passes is 1 hour less or more than the result.