Calendar overview
Use this to spot promising dates and weekends. It is easy to scan but should not be treated as proof of an exact 24-, 36- or 48-hour break.
How to Compare Shift Patterns and Find Real Shared Time Off
Two calendars can both show “rest day” while providing much less shared time than expected. The reliable method is to compare exact working intervals, include every job and exception, and measure the uninterrupted gap between one duty ending and the next duty starting.
Published by: the TimeCalculate team · Last reviewed: 2 September 2026
Start with the question you need answered
“Are we both off on Saturday?” is different from “Do we have 48 continuous hours together?” The first is a calendar-day question. The second must include finish and start times. If one person finishes a night shift at 07:00 on Saturday and returns at 19:00 on Sunday, the shared break is 36 hours even though both dates may contain rest time.
Exact windows
Use start and finish timestamps to plan travel, childcare or events. The window begins after the latest relevant duty finishes and ends when the earliest next duty starts.
Minimum break
Choose a threshold that matches the plan. A short meal, one evening, a full day and a weekend require different minimum lengths.
A simple worked example
Alex works cycle days 1–4 and rests on days 5–8. Sam works cycle days 3–6 and rests on days 7–10. Their common calendar rest days are days 7 and 8. That result is not yet an exact 48-hour window because the last working shift and the next working shift still need times.
| Cycle day | Alex | Sam | Shared status |
|---|---|---|---|
| 5 | Rest | Working | Not shared |
| 6 | Rest | Working | Not shared |
| 7 | Rest | Rest | Potential shared time |
| 8 | Rest | Rest | Potential shared time |
| 9 | Working | Rest | Not shared |
If Sam’s final duty ends at 07:00 on day 7 and Alex’s next duty begins at 07:00 on day 9, the exact common window is 48 hours. If Sam finishes at 10:00 instead, it is only 45 hours and should not qualify when the minimum is set to 48 hours.
Anchor every cycle to a known date
A rota nickname is not enough. “Four on, four off” may mean days only, nights only or a rotating sequence, and different teams can be several cycle days apart. Choose a date whose cycle position is known from the official rota, set it as cycle day one, then verify the next several duties before projecting months ahead.
Multiple jobs belong to one worker
When a person has two jobs, their availability is the complement of both working schedules combined. Enter the primary and secondary roles under the same worker. TimeCalculate merges overlapping working intervals and marks that worker free only when neither job is active. Treating the jobs as two separate people can happen to produce the same all-free intersection in simple cases, but it loses the person-level structure and makes editing and sharing harder to verify.
Overnight duties change the boundary
A night shift belongs to more than one calendar date. If it starts at 19:00 on Friday and finishes at 07:00 on Saturday, Saturday is not fully free. Likewise, the rest period after the last night begins at 07:00, not 00:00. This distinction is the most common reason a coloured rota appears to promise a longer break than the exact result.
Record exceptions instead of forcing the template
Annual leave, training, overtime, court, standby, sickness and swapped duties can change individual dates without changing the underlying cycle. Preserve the repeating pattern for the normal rota, then enter exceptions from the current source record. Do not replace a real calendar with a generic template when the dates disagree.
How to interpret ambiguous entries
- A label such as “training” does not prove a start or finish time. Use the published duty or ask the worker.
- Leave usually replaces a planned duty, but local records may show partial-day leave or another attendance requirement.
- Blank cells may mean rest, missing information or a cropped image. Confirm the legend before treating them as free.
- A duty ending after midnight must carry its true finish into the following date.
Validate a scanned rota before accepting it
- Check that every visible date was captured and is in the correct month and year.
- Compare the first working block, the first rest block and the first overnight transition.
- Check all exceptional labels and any cell without a printed time.
- Confirm the detected cycle reproduces at least one complete visible sequence.
- Review the exact-window list after applying the scan; do not rely only on the coloured calendar.
Scanning is local to the browser. Recognition creates an editable proposal and does not upload the rota image to TimeCalculate. A user remains responsible for confirming that the proposal matches the source.
Final planning checklist
- Use one worker record per person and add every job to that worker.
- Confirm cycle day one from an authoritative date.
- Enter real start and finish times, including overnight finishes.
- Add leave and changed duties that affect the planned period.
- Set the minimum break before judging whether a window qualifies.
- Open exact windows and verify the next result against both source rotas.
- Share only after the comparison is correct; anyone with the complete encrypted link can open it.
For the calculation rules and testing boundaries, read How TimeCalculate produces and checks results. Then use the Friends & Family Shift Calculator to build the comparison.