How to use the rest period between shifts calculator
- List the shifts in date order. For each, pick the date the shift starts and enter the start and end times.
- An end time at or before the start time is read as ending the next day, so an overnight shift needs no extra date.
- Optionally enter a rest threshold in hours from your own policy or contract to flag shorter gaps.
- Read the shortest and longest rest and the table of every gap between one shift's end and the next shift's start.
Formula
Shift end = start date + end time (plus one day when end <= start)
Rest = start of the next shift - end of the shift before it
A rest is flagged when it is shorter than your threshold in hours x 60 minutes
Everything is measured on the calendar clock as entered. Time zones and clock changes are not modeled.
Four shifts with an overnight shift
Monday 3:00 PM to 11:00 PM, then Tuesday 7:00 AM to 3:00 PM, then Tuesday 10:00 PM to 6:00 AM the next day, then Wednesday 2:00 PM to 10:00 PM. The first gap runs from 11:00 PM Monday to 7:00 AM Tuesday, which is 8 hours.
The second gap runs from 3:00 PM Tuesday to 10:00 PM Tuesday, which is 7 hours. The third runs from 6:00 AM Wednesday to 2:00 PM Wednesday, which is 8 hours. The shortest rest is 7 hours. With a threshold of 8 hours entered, only the middle gap is flagged as shorter.
Why overnight shifts need care
A shift that starts in the evening and ends in the morning crosses midnight, so the end time is smaller than the start time. The tool treats that as ending the next day and measures the following gap from the true end. Entering the shifts by start date keeps the order clear.
If the next shift starts before the earlier one ends, the shifts overlap and the tool asks you to fix the entries rather than guessing. For counting the hours inside a shift, use the night shift hours calculator or the hours calculator.
Using your own threshold
Rules about minimum time between shifts differ by place, industry and contract, and some do not exist at all. This tool does not embed any minimum. If your workplace or agreement sets one, type it in and the table marks the gaps that fall short. This is not legal advice, so check the actual rule that applies to you.
To plan a repeating pattern of shifts, the shift rotation schedule generator builds a dated calendar, and the clock out time calculator finds when a shift ends from its start.
Assumptions and limits
- Dates and times are on one clock, with no time zone changes or daylight saving shifts.
- Shifts are listed in date order and do not overlap.
- The threshold is your own number and no legal minimum is built in.
- Breaks inside a shift are not subtracted, because only the gaps between shifts are measured.
Frequently asked questions
How do I calculate the rest period between two shifts?
Subtract the end of the first shift from the start of the next. A shift ending at 11:00 PM and the next starting at 7:00 AM leaves 8 hours.
What if a shift ends after midnight?
Enter the end time as it is, such as 6:00 AM for a shift that began at 10:00 PM. When the end is at or before the start, the tool counts it as the next day.
Is there a legal minimum rest between shifts?
Rules vary by location and job, and some places have none. The tool does not know which applies, so enter your own number and check the rule that governs you.
Can the shifts overlap?
No. If the next shift starts before the previous one ends, the tool shows an error so you can correct the dates or times.