How this calculator works
A dated clock reading only identifies an instant once its offset from UTC is known. This page combines the date, the clock fields and the signed offset into seconds, then subtracts the start from the end. The decimal hours figure is the raw elapsed time divided by 3600, not a payroll-rounded value, so fractions such as 7.75 hours are exact.
Formula
U(x) = 86400 x (O(date) - 1) + 3600h + 60m + s - 3600 x offset_hours. elapsed = U(end) - U(start). decimal hours = elapsed / 3600.
Worked example
09:00 to 17:00 on 2026-10-26 with offset -04:00 at both ends is 28800 seconds, or 8.000000 hours. A 22:00 start to a 06:00 end on the following calendar date with the same offset is also 8 hours, but the end date must be the next date.
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Frequently asked questions
Do I need to change the end date for an overnight shift?
Yes. Enter the actual date on which the shift ends. The calculator does not assume that an earlier clock time means the next morning.
Which offset applies on a daylight-saving night?
Use the offset in force at each reading. A shift through the autumn change can start at -04:00 and end at -05:00, and both are entered separately.
Are unpaid breaks subtracted?
No. This page measures elapsed time only. Use the time-card calculator to subtract unpaid breaks and apply an hourly rate.