Time Duration Calculator: Hours Between Two Times

Working out how long you worked, how long a meeting ran, or how many hours are left before a deadline means subtracting one time from another — and the 60-minute hour makes that fiddly. This guide shows the right way to do it, including overnight shifts that cross midnight. The Time Duration Calculator gives you the answer in hours and minutes instantly, free and in your browser, so timesheets and schedules add up every time.

How duration between two times works

Duration is simply the end time minus the start time. The catch is that time uses base 60, not base 10, so you cannot subtract the digits directly.

The reliable method is to convert both times to minutes since midnight, subtract, then convert back. For example 5:30 PM is 17 hours and 30 minutes, which is 1050 minutes. Subtract the start in minutes, and divide the result by 60 to get hours and the remainder as minutes. If the end is earlier than the start, the period crosses midnight and you add 24 hours.

How to use the Time Duration Calculator

Three quick steps:

1. Open the Time Duration Calculator.
2. Enter the start time.
3. Enter the end time.
4. Read the duration in hours and minutes — overnight spans are handled for you.

There is nothing to install, and the result updates as soon as both times are set. It is ideal for filling in a timesheet line in seconds.

Worked example: a 9:15 to 17:45 shift

You start at 9:15 and finish at 17:45.

Convert each to minutes since midnight:

• 9:15 is 555 minutes
• 17:45 is 1065 minutes

Subtract: 1065 minus 555 = 510 minutes. Divide by 60: 510 / 60 is 8 hours with 30 minutes left over. So the shift is 8 hours 30 minutes. If you knock off a 30-minute unpaid lunch, that is 8 hours of paid time.

Handling overnight shifts

A shift from 22:00 to 06:00 looks like a negative result if you subtract directly, because the end time is a smaller number.

The fix is to recognise the period crosses midnight and add 24 hours:

• 06:00 is 360 minutes, 22:00 is 1320 minutes
• 360 minus 1320 is negative, so add 1440 (24 hours)
• 360 + 1440 minus 1320 = 480 minutes, which is 8 hours

The calculator detects this automatically, so you never have to remember the rule.

When to use it

Time duration comes up across work and life: logging shift hours for payroll, billing clients by the hour, timing how long a task or process took, planning travel between two clock times, or tracking study sessions. Anyone who keeps a timesheet or invoices by time saves real effort with a tool that handles the 60-minute maths and overnight cases for them.

Tips and related tools

Make duration tracking painless:

• Use 24-hour time if your day crosses noon, to avoid AM and PM mix-ups.
• Subtract unpaid breaks separately from the gross duration.
• For decimal hours on an invoice, divide the minutes by 60 — 30 minutes is 0.5 hours.

For a running clock, use the Stopwatch; to total a whole week of shifts, the Time Card Calculator is purpose-built. More options live in the free calculators.

Is it private?

Yes. The Time Duration Calculator computes everything in your browser from the two times you enter, so your work hours and schedules are never uploaded or stored. It needs no account and runs offline once loaded. Discover more free tools that keep your data on your device.