Timezone Converter

Convert a time between cities, with DST handled.

About Timezone Converter

Convert a date and time from one city to another, to up to ten cities at once, or as a start–end range. Daylight saving time comes from IANA time zone data.

How to use

  1. Convert: pick a date and time, choose the From city (your own zone is pre-selected) and the To city (UTC by default). The converted time, its ISO 8601 form and whether each zone is on daylight saving time appear as you change anything. The swap button reverses the direction.
  2. Convert to many zones: enter one time and a base zone, then add up to 10 target cities to see the same instant in each.
  3. Convert a range: enter a start and end in the base zone and up to 10 targets to see the window in every city, for example to schedule a meeting.
  4. Saved cities: keep up to 3 cities with live clocks and their current UTC offset at the top of the page.

What it supports

  • Over 300 cities grouped by region, searchable by city or country name. Each maps to an IANA zone such as America/New_York.
  • Daylight saving rules and historical offsets come from the browser's built-in IANA data, computed with the Luxon library, so a conversion for a date in July uses that date's offset, not today's.
  • A wall-clock time that does not exist, such as 02:30 on a spring-forward night, is reported as an error rather than silently shifted; a time that occurs twice on a fall-back night is converted and a note says which occurrence was used.
  • Results show the zone abbreviation and UTC offset of the converted instant, and the Now button refreshes the time.
  • Results are formatted for your browser locale.

Example

1 Jul 2024, 09:00 in New York → London
→ Converted  1 Jul 2024, 14:00
→ Zone       BST (UTC+01:00)
→ ISO        2024-07-01T14:00:00.000+01:00
→ From zone  Daylight saving time, EDT (UTC-04:00)
→ To zone    Daylight saving time, BST (UTC+01:00)

Privacy

Conversion runs in the page and no request is made. The saved cities list is stored in your browser's localStorage under the key savedTimezones as a JSON array of city labels; nothing else is stored, and Reset removes it.

Frequently asked questions

Why does the time difference between two cities change during the year?
Daylight saving time. New York and London are 5 hours apart in summer but briefly 4 hours apart in March and October, because the two countries switch on different dates. A converter needs the specific date, not just the two zones.
What is the IANA time zone database?
The tz database, maintained by IANA, is the public record of every time zone's offset and daylight saving rules, past and present. Zone names look like Europe/Paris, and operating systems, browsers and most programming languages ship a copy of it.
Why should I use a city name instead of an abbreviation like EST or IST?
Abbreviations are ambiguous: IST means Indian, Irish or Israel Standard Time, and EST does not tell you whether daylight saving applies. A city maps to one IANA zone with exact rules.
What is the difference between UTC and GMT?
For everyday purposes they are the same time. UTC (Coordinated Universal Time) is the atomic-clock standard that time zones are defined against; GMT is the older name for the zone at zero offset, still used in the United Kingdom in winter.