How this calculator works
A shift is a duration placed on a calendar. The start boundary is turned into a whole number of seconds from a fixed epoch, the shift length is added or removed, and the result is split back into a date and a clock time. Because dates are carried explicitly, a shift that runs past midnight ends on the next date instead of wrapping silently. Paid hours subtract only the unpaid break you enter.
Formula
instant = 86400 x (day number - 1) + 3600h + 60m. For a shift end: end = start + length. For a shift start: start = end - length. For a length: length = end - start. paid hours = (length - 60 x break minutes) / 3600.
Worked example
A shift starting at 09:00 with an 8-hour length ends at 17:00, and a 30-minute break leaves 7.5 paid hours. A shift from 22:00 on one date to 06:00 on the next is 8 hours long, not a negative value.
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Frequently asked questions
Does the length include or exclude the break?
The length is the full time between the start and end boundaries, so it includes the break. Paid hours subtract the break. Enter 8 hours, not 7.5 hours, for an eight-hour shift with a half-hour unpaid break.
What if my shift crosses midnight?
Enter the real end date. The calculation uses both dates, so 22:00 to 06:00 the following morning is measured as eight hours. It does not guess that an earlier clock time means the next day.
Is this the same as a payroll time card?
No. It handles one shift and one break. The time-card calculator can combine several shifts, check for overlap and apply an hourly rate. Provincial rules on breaks and overtime are not applied here.
Can I use a shift length in minutes?
Yes. The length field has hour and minute units. Enter 450 minutes and it is treated as 7.5 hours.