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Time duration calculator

How long between two times? Add up hours and minutes, and get decimal hours for timesheets.

Decimal places in decimal hours

Show clock times as

How long between two times?

Works across midnight: an end time earlier than the start counts as the next day.

Optional

Optional, for spans longer than a day

Enter a start time and an end time to see how long it is.

Add up durations

Totals a list, like the hours on a timesheet. Start a line with a minus sign to subtract it.

Write each as 1:30, 2h 15m or 90 minutes. Up to 200 lines.

Enter at least one duration to see the total.

What time is it after a duration?

Move a clock time forward or back, like a meeting that runs 3 hours 45 minutes.

Enter a start time and a duration to see the new time.

At a glance

What it does
Three calculators: the time between two clock times, a total of several durations, and a clock time moved forward or back by a duration.
Across midnight
An end time earlier than the start counts as the next day: 10:00 PM to 6:00 AM is 8 hours.
Breaks
Take off an unpaid break in minutes, and add whole extra days for spans longer than a day.
Results
Hours and minutes, a clock reading like 7:30, decimal hours like 7.5, and total minutes.
What you can type
Times like 9:30 am, 21:45, 0930 or noon. Durations like 1:30, 2h 15m, 90 minutes or 1.5 hours.
Limits
Plain 24 hour clock arithmetic. It does not know about daylight saving or time zones.
Privacy
Nothing is sent when you type. Your entries are kept in the page address so a link can be shared, so a shared link carries them.

How to do it

  1. 1

    Pick the question

    Use How long between two times? for a shift or a trip, Add up durations for a list of hours, or What time is it after a duration? to move a clock time.

  2. 2

    Enter your times or durations

    Type them in any of the forms above. A line under each box says how it was read, such as Read as 5:30 PM.

  3. 3

    Set the display

    Choose 1 to 4 decimal places for decimal hours, and whether clock times show as 12-hour or 24-hour.

  4. 4

    Read the result and the working

    The big line is the answer in words. The facts and the numbered working show hours and minutes, decimal hours and each subtraction.

The time between two clock times

The calculator turns each time into seconds since midnight and subtracts. 9:00 AM to 5:30 PM is 17:30 minus 09:00, which is 8 hours 30 minutes. An unpaid break comes off the end: with a 30 minute break the answer is exactly 8 hours. If the two times are the same, the answer is 0. For a full 24 hours, add 1 in Extra whole days.

Across midnight and over several days

When the end time is earlier than the start, the end is counted as the next day. The working adds 24 hours to the end first: 6:00 AM becomes 30:00, and 30:00 minus 22:00 is 8 hours. For a span of more than a day, put the extra whole days in the box. 10:00 AM to 8:00 AM the next day is 22 hours, and with 1 extra day it is 46 hours, which the page also writes as 1 day and 22 hours.

Decimal hours for timesheets

Timesheets and invoices often want hours as a decimal, where 7.5 means 7 hours 30 minutes. To convert, divide the minutes by 60. The common ones are worth knowing:

  • 6 minutes is 0.1 hours, 15 minutes is 0.25, 30 minutes is 0.5 and 45 minutes is 0.75.
  • 20 minutes is 0.33 hours, from 20 ÷ 60 = 0.3333, rounded for display.
  • 7 hours 20 minutes is 7.33, and not 7.20. A figure like 7.20 would mean 7 hours 12 minutes.

Decimal hours are kept as exact fractions and rounded once, when shown. The working uses ≈ when a figure is rounded, and the decimal places setting changes only the display. The one exception is a very small amount: it keeps enough digits to stay above 0, so one minute reads 0.017 hours even with 1 decimal place.

What clock arithmetic cannot know

This is plain clock arithmetic on a 24 hour day. It does not know about daylight saving time or time zones. Where clocks change, a shift from 10:00 PM to 6:00 AM really lasts 7 or 9 hours on the night of the change, not 8. If you need that precision, use the real start and end moments, or adjust the result by the hour the clocks moved.

For times in different places, convert both to the same time zone first, then subtract. To count whole days between dates instead, see the date difference calculator.

Questions people ask

How do I calculate the hours between two times?

Subtract the start from the end on a 24 hour clock. From 9:00 AM to 5:30 PM, 17:30 minus 09:00 is 8 hours 30 minutes, or 8.5 decimal hours. Enter both times in the first box and the answer appears with the working, and an optional break comes off the total.

How do I calculate time across midnight?

Add 24 hours to the end time when it is earlier than the start, then subtract. 10:00 PM to 6:00 AM is 30:00 minus 22:00, which is 8 hours. The calculator does this for you and says the end is on the next day.

How do I convert hours and minutes to decimal hours?

Divide the minutes by 60 and add the result to the hours. 7 hours 45 minutes is 7 + 45 ÷ 60 = 7.75. In the first two boxes the decimal hours are shown for you, with 1 to 4 decimal places.

Can I add several times together?

Yes, in Add up durations. Put one duration on each line, like 1:30 or 2h 15m, and start a line with a minus sign to subtract it. A bare number such as 90 is refused, because it could mean minutes or hours. Write 90m or 1.5h.

Does it handle daylight saving time?

No. It uses plain clock times on a 24 hour day, so it cannot know that an hour was skipped or repeated. On a night when clocks change, the real time between two clock readings is an hour more or less than the answer here.

Is anything I type stored or sent?

No. Typing sends nothing anywhere: the sums run in your browser. Your times and durations are also kept in the page address so that Copy link works. That means a link you share, or a page you reload, requests that address, entries included, from our server like any web address. Share a link only if you are happy to share what you entered.

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