gizmobench

Time Calculator

Type durations one per line, plus or minus, and this adds them up as you go: the total is shown as a clock, in decimal hours and in minutes at the same time, and a start time turns it into a finishing time that says when it has crossed midnight. Every line reads the way people actually type time, so 1:45, 1:45:00, 1h 30m 20s, 90 and 2.5h all work, and a note can sit beside each one. This is the tool for arithmetic on lengths of time. For a time card of clock-in and clock-out times with breaks and rounding, use the hours calculator; for the time between two dates, use the duration calculator.

Entries0 lines · Enter adds a line
Total0:00:00One duration per line: 1:45, 1h 30m, or 90 for minutes
Format
Start from
End time
needs a start

One duration per line. Write 1:45 or 1:45:00, 1h 30m 20s, 90 for ninety minutes, or 2.5h. A leading minus takes the line off the total, and anything after two spaces or a # is a note that is kept but not counted.

Durations, not shifts and not dates. This page adds and subtracts lengths of time. For clock-in and clock-out times with breaks and payroll rounding, use the hours calculator; for the time between two dates, the duration calculator. Every line is parsed to whole seconds and the total is exact; decimal hours are rounded to two places. Adding to a start time wraps past midnight and says so.

Common questions

What time formats can I type?
Three forms, and they can be mixed on one list. Colon form: 1:45 is hours and minutes and 1:45:00 is hours, minutes and seconds, always in that order, so a 30 second clip is 0:00:30. Unit form: 1h 30m 20s, in any order and with or without the spaces, and a decimal with a unit such as 2.5h is that unit. A plain number is minutes, so 90 is an hour and a half. A line can start with a plus or a minus, and anything after two spaces or a # is a note that is kept beside the line and not counted. A form the tool cannot read is named on the page with its line number, and the other lines still count.
Can the total be negative?
Yes. A leading minus takes a line off the total, which is how a break comes out of a list you have already typed, and if the subtractions outweigh the additions the total is shown with a leading minus: 0:30 minus 1:00 is -0:30:00, which is -0.50 decimal hours and -30 minutes. Nothing is clamped to zero.
How do I convert a time to decimal hours?
Divide the minutes by 60 and add the hours: 4:30 is 4.5 hours, 4:15 is 4.25 and 4:20 is 4.33. The decimal on this page is rounded to two places, half up, while the seconds behind it stay exact, so 4:32:30 shows as 4.54 and the h:mm:ss form still reads 4:32:30. The minutes figure is exact too: 4:32:30 is 272.5 minutes.
How do I work out what time I will finish?
Type a start time in the Start from box, in 24-hour HH:MM such as 09:00 or 17:30, and the finishing time appears beside it and in the list below. Adding past midnight wraps and says so: a 23:30 start plus 1:00 ends at 00:30 the next day, and a total of more than a day says how many days later. A negative total runs backwards, and going back past midnight is marked as the day before.
What is the difference between this, the hours calculator and the duration calculator?
They are three different jobs on the same site. This page does arithmetic on lengths of time: a running list of durations, added and subtracted. The hours calculator is a time card: clock-in and clock-out times, breaks, payroll rounding and overtime counts. The duration calculator finds the time between two dates and times. Each one links to the other two.
Are my entries saved anywhere?
They stay in this browser and go nowhere else. The list, the format and the start time are kept on this device so the page is still filled in when you come back, and nothing is uploaded, because the whole tool runs in the browser and there is no account to make.

Every line is parsed to whole seconds and the total is exact; decimal hours are rounded to two places. Adding to a start time wraps past midnight and says so.