Time Duration Calculator
Enter a start time and an end time and get the exact duration between them — overnight shifts that cross midnight are detected automatically, so a start of 22:00 and an end of 06:00 correctly comes out to 8 hours, not a negative number.
Minutes in, minutes out — with one adjustment for midnight
Both times are converted to minutes since midnight (an hour field times 60, plus the minute field), and the duration is just the end minus the start. The only wrinkle is what happens when that subtraction goes negative — which happens whenever the end time, read purely as a clock face, is earlier than the start time. Rather than show a negative duration, this tool assumes the shift crossed into the next calendar day and adds a full 24 hours (1440 minutes) back in before reporting the result, and flags it with a "Crosses midnight" note so it's never a silent assumption.
Worked examples
Overnight shift: start 22:00, end 06:00. As raw minutes: 1320 and 360. 360 − 1320 =
−960, which is negative, so 1440 is added back: 480 minutes —
exactly 8:00 (8.0 decimal hours), and the
midnight badge appears.
Same-day shift: start 09:15, end 17:45. As raw minutes: 555 and 1065. 1065 − 555 =
510 minutes, no adjustment needed — 8:30 (8.5
decimal hours), the exact number a payroll timesheet would
expect for a shift with a 30-minute remainder.
Frequently asked questions
How does this handle an overnight shift?
If the end time is earlier than the start time, the calculator assumes the end time falls on the next day and adds 24 hours before finding the difference — so 22:00 to 06:00 correctly returns 8 hours, not a negative number. When this happens, a "Crosses midnight" note appears above the result so you know why the calculated span is longer than the two clock times might suggest at a glance.
Why do I get a decimal-hours figure too?
Timesheets and payroll systems usually want decimal hours (like 8.5) rather than hours and minutes (8:30) — 30 minutes is exactly half an hour, so it becomes .5, and 45 minutes becomes .75. This tool calculates both from the same result so you don't have to convert by hand.
Does this account for seconds?
No — it works to the minute, matching what a standard HH:MM time picker gives you. If you need second-level precision, you're likely timing something a stopwatch or a script should be doing instead.
What if I enter the same time for both fields?
The result is 0 hours 0 minutes — the calculator assumes no time has elapsed rather than a full 24-hour day, since that's the more common intent when both fields match, whether by mistake or by design (like checking an empty schedule slot).