Time Zone Converter

See any moment in multiple time zones at once, with working hours indicators.

America/New_York-04:00Sat, Jul 4, 7:13 AM EDT
Europe/London+01:00Sat, Jul 4, 12:13 PM GMT+1
Asia/Tokyo+09:00Sat, Jul 4, 8:13 PM GMT+9
local · 0.22ms · 48 bytes processed · 3 zones

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How it works

Enter a date, time, and source time zone. Add any number of target zones from a searchable list of all IANA time zones (powered by Intl.supportedValuesOf). The tool converts the moment to a UTC instant, then formats it in each target zone using Intl.DateTimeFormat — the same engine browsers use for locale-aware date display. A working hours dot shows green for 09:00–17:00 in that zone and grey outside. All computation is local, with no external API.

Common use cases

  • Schedule a meeting between Sydney, London, and San Francisco — see all three local times at once.
  • Find the best time to call family abroad without staying up past midnight.
  • Coordinate a software release across engineering teams in different continents.

Frequently asked questions

How are DST transitions handled?

The Intl.DateTimeFormat engine knows every zone's historical and future DST rules. Enter a date during a DST transition and the result is correct automatically — no manual offset adjustment needed.

Where does the zone list come from?

Intl.supportedValuesOf('timeZone') returns all IANA zones supported by your browser (typically 400–600 entries). These are the canonical names like America/New_York and Asia/Ho_Chi_Minh — not abbreviations like EST, which are ambiguous.

What counts as working hours?

The green dot shows when the local time in that zone falls between 09:00 and 17:00 (inclusive of 09:00, exclusive of 17:00). This is a rough heuristic — adjust for your team's actual hours.

Why not use EST or PST abbreviations?

Timezone abbreviations are ambiguous — CST means China Standard Time, Central Standard Time, and Cuba Standard Time. IANA zone names are unambiguous. The display time uses a short abbreviation for readability, but zone selection uses IANA names.