Work, pay & shifts
How to Calculate Shift Overlap Hours
When one shift hands off to the next, the two often overlap so the outgoing worker can brief the incoming one. Working out that overlap is a one-line calculation once both shifts are on the same timeline. This guide shows the rule, the steps for any pair of shifts, and how to turn the result into decimal hours.
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The rule: later start to earlier end
Two shifts overlap from whichever starts later until whichever ends earlier. A 7:00 AM to 3:30 PM shift and a 3:00 PM to 11:30 PM shift overlap from 3:00 PM to 3:30 PM: 30 minutes. If the earlier end comes before the later start, there is no overlap — there is a gap instead.
Putting both shifts on one timeline
- Write each time as minutes after midnight on the day Shift A starts: 3:30 PM is 930.
- If a shift ends at or before its start time, add 1,440 minutes (24 hours) to its end.
- If Shift B starts the next day, add 1,440 to both of its times.
- Overlap = the smaller end − the larger start, or 0 if that is negative.
Examples
| Shift A | Shift B | Later start | Earlier end | Overlap |
|---|---|---|---|---|
| 7:00 AM – 3:30 PM | 3:00 PM – 11:30 PM | 3:00 PM | 3:30 PM | 30 minutes |
| 6:45 AM – 3:15 PM | 3:00 PM – 11:30 PM | 3:00 PM | 3:15 PM | 15 minutes |
| 8:00 AM – 6:00 PM | 10:00 AM – 2:00 PM | 10:00 AM | 2:00 PM | 4 hours |
| 6:00 AM – 2:00 PM | 2:00 PM – 10:00 PM | 2:00 PM | 2:00 PM | 0 minutes |
Overlap in decimal hours
Timesheets and staffing models often need hours as decimals: divide the minutes by 60. 15 minutes is 0.25 hours, 30 is 0.5, 45 is 0.75, and 20 minutes is about 0.33.
When one shift sits inside another
A short shift that starts after and ends before a longer one — a 10:00 AM to 2:00 PM helper during an 8:00 AM to 6:00 PM shift — overlaps for its whole length. The same rule gives the right answer: later start 10:00 AM, earlier end 2:00 PM, 4 hours.
Calculating Shift Overlap FAQ
- What is shift overlap?
- The time when two consecutive shifts are both on duty, usually so the outgoing worker can hand over to the incoming one.
- How do I calculate overlapping hours in Excel or Google Sheets?
- With times in cells, use =MAX(0, MIN(endA, endB) − MAX(startA, startB)) × 24 for hours. For a shift that ends after midnight, add 1 to its end time first.
- Are overlap hours counted twice in labor hours?
- Yes. Both people are on duty, so both are working — overlap adds to the total hours a schedule uses.
- What if there is a gap between the shifts?
- The calculation gives zero overlap; the gap is the later start minus the earlier end.
- Should a break during the handoff be subtracted?
- Only from the person taking the break. The overlap measures when both shifts are scheduled; breaks are a separate deduction from each person’s hours.
Related guides
- Overnight Shift HandoffsLine up night shifts with the shifts around them: which day the next shift starts, two overnight shifts, daylight saving nights, and dates in schedules.
- Shift Overlap Over a YearTurn a 15- or 30-minute handoff overlap into hours and cost per week and per year, and keep a good handover without paying for more overlap than it needs.
Open the tool
Jump into Shift Handoff Overlap Hours Calculator when you are ready to process your files.
