Examples
Examples
Try the starting example
- Planned check-ins: name, local date, local HH:MM
- Day 1,2026-10-20,18:00 Day 2,2026-10-21,18:00
- Fixed local UTC offset (minutes)
- 60
- Minutes each side of expected time
- 30
- Contact availability: UTC start timestamp, UTC end timestamp
- 2026-10-20T16:00:00Z,2026-10-20T18:00:00Z 2026-10-21T19:00:00Z,2026-10-21T20:00:00Z
- Planned UTC check-in windows
- Day 1: 2026-10-20T16:30:00.000Z to 2026-10-20T17:30:00.000Z; Day 2: 2026-10-21T16:30:00.000Z to 2026-10-21T17:30:00.000Z
- Windows not fully covered by contact availability
- Day 2
- Fully covered check-in windows
- 1
Try another scenario
- Planned check-ins: name, local date, local HH:MM
- Day 1,2026-10-20,18:00 Day 2,2026-10-21,18:00
- Fixed local UTC offset (minutes)
- 60
- Minutes each side of expected time
- 30
- Contact availability: UTC start timestamp, UTC end timestamp
- 2026-10-20T00:00:00Z,2026-10-22T00:00:00Z
- Planned UTC check-in windows
- Day 1: 2026-10-20T16:30:00.000Z to 2026-10-20T17:30:00.000Z; Day 2: 2026-10-21T16:30:00.000Z to 2026-10-21T17:30:00.000Z
- Windows not fully covered by contact availability
- None
- Fully covered check-in windows
- 2
Calculation method
Calculation method
Planned UTC check-in windows
Convert each supplied local civil time to UTC using the fixed numeric offset; subtract/add the chosen half-window minutes.
Windows not fully covered by contact availability
Merge overlapping or touching availability rows for the same contact, then require a merged interval to contain the entire check-in window.
Fully covered check-in windows
Count check-in windows wholly covered by the merged contact availability.
Symbols and units
- a
- Planned check-ins: name, local date, local HH:MM
- b
- Fixed local UTC offset (minutes)
- c
- Minutes each side of expected time
- d
- Contact availability: UTC start timestamp, UTC end timestamp
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- A static timetable comparison with fixed UTC offsets. It does not send reminders, track a trip, verify a contact’s response or provide an emergency monitoring service.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
OpenStax: arithmetic and geometry ↗
Background reading; this does not imply endorsement or independent review of SumFizz.