Timezone Overlap Calculator
Find shared working hours across up to 5 time zones. Essential for scheduling distributed team meetings without the back-and-forth.
Select your team's time zones
Working hour overlap
All zones overlap
Working hours
Outside working hours
How to use the timezone overlap calculator
Select your home time zone in the first dropdown, then add your teammates' time zones one by one. The calculator maps a 7am–7pm working window for each zone and highlights every hour that falls within that window for all selected zones simultaneously.
Working windows outside typical hours (before 7am or after 7pm) are intentionally excluded — technically available but rarely realistic for sustained collaboration. For genuinely async-first teams, the tool still shows where overlap exists if needed for emergencies.
FAQ
How does the timezone overlap calculator work? +
The calculator uses your browser's built-in Intl.DateTimeFormat API to convert the standard 9am–5pm working window into each selected time zone, then highlights hours that overlap across all zones. No data is sent to any server.
What counts as a working overlap? +
We define working hours as 07:00–19:00 in each time zone. An overlap hour is one that falls within the working window for every team member simultaneously. For scheduling calls, a minimum of 1 overlapping hour is generally workable; 2–3 hours is comfortable.
Can I save my timezone selection? +
Yes. Your last selection is automatically saved using browser sessionStorage, so it persists within the same browser session. For permanent bookmarking, note your selections and re-enter them on return.
Which time zones are supported? +
The calculator supports all IANA standard time zones, covering every country and region worldwide — including zones with non-standard offsets like India (UTC+5:30) and Nepal (UTC+5:45).
Does the calculator account for daylight saving time? +
Yes. The Intl.DateTimeFormat API automatically handles DST transitions for each zone based on today's date. Results will shift automatically when DST changes in any selected zone.