Time Calculator

The Calculate menu switches between two modes. The default adds or subtracts durations, and the second finds the gap between two clock times, which is the one to use for shifts.

1. Leave Calculate on Add or subtract durations, then fill in Days, Hours, Minutes and Seconds for the first duration. The starting values are 0 days, 2 hours and 30 minutes.
2. Choose the Operation: Add or Subtract.
3. Enter the second duration in Days to add or subtract, Hours to add or subtract, Minutes to add or subtract and Seconds to add or subtract. It starts at 1 hour and 45 minutes. Hours and minutes accept decimals, so 1.5 hours works.
4. Read the total at the top, then the same value as hours, minutes and seconds, as decimal hours, as total minutes, as total seconds and as days.
5. For a work shift or a trip, change Calculate to Time between two clock times and pick a Start time and an End time.
6. Type any Unpaid break (minutes) to see the time after the break, both as hours and minutes and as decimal hours.

Mixing days, hours, minutes and seconds is awkward because each unit rolls over at a different number. The calculator avoids that by turning everything into seconds, doing the sum, and converting back. A day is 86,400 seconds, an hour is 3,600 and a minute is 60.

With the starting values, 2 hours 30 minutes is 9,000 seconds and 1 hour 45 minutes is 6,300 seconds. Added together they make 15,300 seconds, which the tool shows as 4 hours, 15 minutes, written 4:15:00 on a clock face. The same total is 4.25 decimal hours, 255 minutes and about 0.1771 days.

If the second duration is longer than the first when you subtract, the answer is negative. One hour minus two hours gives -1 hour, shown with a minus sign and a note that the second time is longer. That is useful for checking how far over or under a budget of time you are.

Timesheets often need decimal hours rather than hours and minutes, because pay is multiplied by hours worked. Dividing the minutes by 60 gives the decimal:

A value such as 7 hours 20 minutes is therefore 7.33 hours, not 7.20. Mistaking one for the other is the most common timesheet error, and the Decimal hours line removes the guesswork. To convert a single figure quickly, the hours to minutes and minutes to hours converters do just that.

In Time between two clock times mode the tool subtracts the start from the end. For 09:15 to 17:40 the gap is 8 hours 25 minutes, which is 505 minutes or 8.42 decimal hours. Enter a 30 minute unpaid break and the time after the break becomes 7 hours 55 minutes, or 7.92 hours. Multiply that by an hourly rate for gross pay, or turn a salary into an hourly figure with the salary to hourly calculator.

If the end time is earlier than the start, the tool assumes the end falls on the next day. A night shift from 22:00 to 06:30 is therefore 8 hours 30 minutes. Equal start and end times give 0 minutes, not 24 hours, and a break longer than the gap produces a warning instead of a negative number.

There are limits to know about:

• It does not know about time zones or daylight saving changes, so a journey across zones needs the time zone converter.
• It adds durations to each other. It does not add a duration to a clock time of day, so it will not tell you what the time will be in 3 hours.
• The time pickers use 24 hour times, although your browser may display AM and PM.
• To count days between two calendar dates, use the date difference calculator, or the date calculator to move a date forward.

Everything is computed on your device from the numbers you type, with no account and nothing stored.