world-clock-converter
A world clock converter shows current and future local times side-by-side across multiple cities — designed for distributed teams scheduling meetings, travellers planning calls home, and anyone trying to find a slot that does not put a teammate in the middle of dinner. The ZTools World Clock Converter pins your favourite cities, draws a 24-hour heatmap so overlapping working hours are obvious at a glance, supports DST awareness, and emits a shareable URL containing the cities + the chosen meeting time so calendar invites become unambiguous.
Use cases
Distributed-team standup scheduling
A team in SF / NYC / London / Berlin / Bangalore has 4 working-hour overlaps per day. The heatmap surfaces them so the standup lands inside everyone's 09:00–17:00 local.
Cross-border client calls
Schedule a 1-hour call between you and a client. Drag the meeting band across the heatmap until both ends sit in 09–17.
Family / personal calls
Living abroad — when is "good morning here" still "before bed there"? The world clock makes the answer obvious without mental math.
Travel planning
Multi-leg trip across timezones; pin each destination ahead of time so jet-lag math is one glance away.
How it works
- Pin cities — Search by name; pin to the panel. Default order: home city first, then by UTC offset.
- View the heatmap — A 24-hour grid where each pinned city's "working hours" (09–17 by default) is highlighted. Overlapping bands are visually obvious.
- Drag a meeting time — Click any column to set a candidate meeting hour. The corresponding local time shows for each city; out-of-hours cells warn with a different colour.
- Adjust for DST — Each city shows current DST status and the next shift date. The heatmap updates automatically when DST flips.
- Share — Generate a shareable URL containing the city list + the proposed time. Recipients see the same view in their local zone.
Examples
Input: Pinned: SF, NYC, London, Berlin, Mumbai
Output: Heatmap shows three overlapping bands (08:00–09:00 PT / 11:00–12:00 ET / 16:00–17:00 GMT / 17:00–18:00 CET / 21:30–22:30 IST)
Input: 14:00 UTC meeting time
Output: SF 07:00, NYC 10:00, London 15:00 (BST), Berlin 16:00, Mumbai 19:30
Input: After EU DST end
Output: Berlin shifts back 1 hour; the heatmap updates to reflect new overlap windows
Frequently asked questions
How is this different from a single timezone converter?
A single converter answers "what is X in zone Y?". The world clock answers "what hour works for everyone?" — the visual heatmap is the difference, especially when 5+ cities are involved.
Can I customise working hours per city?
Yes — set 09–17 globally or per-city (e.g., NYC 08–16, Mumbai 10–18). Heatmap respects each city's window.
Does it handle DST?
Yes — IANA tzdata. Both directions: spring-forward and fall-back. Future-date previews honour the published rules.
How accurate is "future date" mode?
Through 2030 the rules are stable. Beyond that, some countries' DST rules are tentative; double-check for long-range planning.
Can I save my pinned cities?
Yes — pinned set persists in browser local storage. Optional shareable URL captures the same set for collaborators.
Does it auto-detect my city?
Optionally, by browser timezone. Manual override always works.
Tips
- Pin your home city first — every other time becomes relative to "you".
- Set custom working-hour windows per city; some teams run 10–18 (Mumbai), others 08–16 (NYC).
- For meetings, send the shareable URL — recipients see times in their own zone, no mental math.
- Watch for DST transitions in either zone — meeting times "every Tuesday at 15:00 GMT" can shift relative to other cities at the boundaries.
- For 5+ cities, accept that perfect overlap is rare — pick the time with fewest people inconvenienced.
Try it now
The full world-clock-converter runs in your browser at https://ztools.zaions.com/world-clock-converter — no signup, no upload, no data leaves your device.
Last updated: 2026-05-05 · Author: Ahsan Mahmood · Edit this page on GitHub