Shift Calculator

This shift calculator finds a work shift start time or end time from the information you already know. It supports known start time or known end time, a shift duration, duration units, and break duration in minutes. Results show the full shift span, effective working time, total clock duration, and break percentage.

How to use this calculator

Select whether you know the start or end time. Enter the time in HH:MM 24-hour format, such as 07:30 or 15:30. Then enter the shift duration, choose minutes, hours, or hours and minutes, and add total break minutes. For full weekly totals, use the time card calculator.

How it works

The calculator converts the duration to minutes, adds unpaid break minutes to get the clock span, then counts forward or backward from the known time.

paid hours = end time - start time - unpaid breaks

$clock\ span = working\ minutes + break\ minutes$

$end\ time = start\ time + clock\ span$

or

$start\ time = end\ time - clock\ span$

Worked example

If a shift starts at 07:30, lasts 8 hours, and includes a 30-minute break, the effective time is 8h 0m and the total duration is 8h 30m. The end time is 16:00.

Scheduling tips

Use 24-hour time to avoid AM and PM confusion. If you are measuring elapsed time rather than a work shift, use the time duration calculator. For meetings across regions, the time zone calculator is safer than adding offsets manually.