THE NUMBERS, EXPLAINED
How to use this calculator.
Checks one-hour UTC slots whose starts fall within both local work windows during the selected UTC day. Both locations use the same entered working hours; no holiday or availability data is connected.
Start with your inputs
Enter meeting date (utc day), iana time zone a, iana time zone b, start work hour, end work hour. Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Meeting date (UTC day) | 2026-01-15 |
| IANA time zone A | Europe/London |
| IANA time zone B | America/New_York |
| Start work hour | 9 |
| End work hour | 17 |
A worked example
With the example inputs above, available utc start hours is 14:00Z, 15:00Z, 16:00Z. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Available UTC start hours | 14:00Z, 15:00Z, 16:00Z |
How this is calculated
Available UTC start hours
overlapSlots(a,b,c,d,e)
Symbols and units
- a
- Meeting date (UTC day)
- b
- IANA time zone A
- c
- IANA time zone B
- d
- Start work hour
- e
- End work hour
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
Check each of the 24 whole-hour UTC slots on the chosen UTC date. Convert that instant into each IANA timezone and retain it if both local hours fall in the working window, including its start and excluding its end. This is an hourly scan, not minute-level overlap.
Assumptions and limits
Checks one-hour UTC slots whose starts fall within both local work windows during the selected UTC day. Both locations use the same entered working hours; no holiday or availability data is connected.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Available UTC start hours. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Checks one-hour UTC slots whose starts fall within both local work windows during the selected UTC day. Both locations use the same entered working hours; no holiday or availability data is connected.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
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