Timezone overlap calculator
UTC offsets and local 9–5 (or your hours). Overlap listed as UTC hours both sides are at work.
Find shared working hours across offsets
Cross-timezone booking fails when agents ignore local work windows. Enter two UTC offsets and shared local hours to see which UTC hours both sides are at work.
How to use the timezone overlap calculator
Set offset A and B (for example −5 and +1), then work start/end in local hours. Read the overlapping UTC hours — or “no overlap” if async is safer. For DST-aware zones, resolve offsets from IANA names first.
Offsets and work hours
2 overlapping UTC hours
14:00, 15:00
What the result means
Overlapping UTC hours are candidate meeting slots under the fixed offsets you entered. Apply booking buffers inside that window, and recompute when DST changes an offset.
FAQ
How does this timezone overlap calculator work?
You enter two fixed UTC offsets and shared local work start/end hours. For each UTC hour 0–23, it converts to each side’s local hour and lists UTC hours when both are inside the work window.
Is this the same as the IANA time zone database?
No. The IANA Time Zone Database (tzdb) defines named zones (for example America/New_York) including daylight-saving rules. This tool uses fixed numeric UTC offsets only — it does not apply DST transitions. For production scheduling, convert named zones with a DST-aware library, then compare windows.
Why list overlap in UTC hours?
UTC is a shared reference so both sides can map the same instant. Once you know which UTC hours overlap, an agent can propose local times or calendar invites without guessing.
What if there is no overlap?
The tool reports no overlapping UTC hours. Prefer async updates, handoff notes, or split coverage — do not force a meeting that sits outside someone’s work hours.
How should booking agents use this with buffers?
Find the overlap window first, then apply booking buffers so each slot still fits wrap/travel time inside that window. Pair with no-show risk for reminder timing.
Need booking that respects shared work hours?
GoWith agentic builds propose slots inside real overlap windows. See all free tools, the booking buffer calculator, the meeting cost calculator, and the no-show risk calculator.
Educational only. Not legal advice and not a substitute for testing the live agent. Timezone overlap calculator runs in your browser — nothing is sent to your CRM unless you copy it yourself.