Timezone Converter
Convert a date and time between timezones and line up a meeting across cities — DST-aware, entirely on this device.
0 timezones — type a city or zone name and pick from the list.
Pick a date, a time and two zones — the converted time appears here.
Press ? for shortcuts
Do it offline:$ TZ="Asia/Tokyo" date
How to use it
- Pick the date and time in the first field — this is the wall clock in the source zone, the one the organizer is looking at.
- Choose the source and target zones. Typing searches city names inside IANA identifiers, so "new york" finds America/New_York.
- Read the headline: the target city's local time, weekday, that date's UTC offset, and a day badge whenever the calendar date differs from the source.
- Add up to six more zones to cover the rest of the invite list; every row updates together, and Swap reverses the pair.
- Copy the readings as text, download them, or use Share to hand the exact meeting to someone else as a link.
Set the meeting's date and time once, in the organizer's zone, and read what every attendee's clock will say — target city first, then a planner strip for up to six more zones. Hour gaps are computed for that exact date, so daylight-saving season shows up as a different number instead of a missed call. When the plan is ready, share it as a link or copy the whole strip.
How it works
A timezone identifier such as America/New_York names a place and its entire rulebook — every UTC offset the region has used or scheduled, as published in the IANA Time Zone Database. Three-letter labels like EST name a single offset with no calendar attached, so they cannot answer a question that depends on the date. This tool takes identifiers in and prints each row's numeric offset out, valid for the day you picked.
Under the hood there is exactly one moment being described. The converter anchors your date and time to the source zone's rules to find that single instant, then asks every other zone what its clocks read at the same instant. Nothing is added or subtracted between cities directly — each reading is derived from the one shared moment, which is why the weekday and even the calendar date can differ from row to row.
The familiar phrase "n hours ahead" is only ever true for a stretch of the calendar. Every jurisdiction schedules daylight saving on its own calendar — March and November in one country, October and April in another, never at all elsewhere — so a pair of cities can sit nine, ten and eleven hours apart within the same year. The difference sentence on this page is therefore computed from the requested date, never quoted from a fixed table.
On the day a zone changes offset, its wall clocks misbehave in one of two ways: a span of local time is skipped entirely, or a span is lived through twice. A meeting placed in a skipped span cannot happen as written, and one placed in a repeated span names two possible instants. The converter states which case you hit, shows both real alternatives with their offsets, and lets you pick either — it never resolves the ambiguity silently.
Examples
2026-08-07 09:00 America/New_York → Asia/Tokyo22:00 Friday 2026-08-07 in Tokyo (UTC+09:00) — same day, 13 h aheadThe sample meeting: nine in New York is a same-day 22:00 in Tokyo, thirteen hours ahead on this date. On 2026-01-15 the same pair is fourteen hours apart — the gap itself is seasonal.
2026-01-15 16:00 Europe/London → America/Los_Angeles + Asia/Kolkata + Australia/SydneyLos Angeles 08:00 Thursday 2026-01-15 (UTC-08:00)
Kolkata 21:30 Thursday 2026-01-15 (UTC+05:30)
Sydney 03:00 Friday 2026-01-16 (UTC+11:00) +1 dayOne strip covers the whole invite list: Los Angeles is still at breakfast, Kolkata sits on its half-hour offset at 21:30, and Sydney has already crossed into Friday — the +1 day badge is data, not decoration.
2026-03-08 02:30 America/New_York → Europe/LondonShifted to 03:30 Sunday 2026-03-08 (UTC-04:00) — London reads 07:3002:30 never happens in New York that morning — clocks jump from 02:00 straight to 03:00. The converter moves forward to 03:30, prints the warning verbatim, and offers 01:30 at UTC-05:00 as the before-the-gap alternative.
2026-11-01 01:30 America/New_York → Europe/London01:30 kept at UTC-04:00 → London 05:30; the later 01:30 (UTC-05:00) would be 06:30The mirror image of the skipped hour: 01:30 on 2026-11-01 occurs twice in New York. The earlier instant is the default, and choosing the later one moves London from 05:30 to 06:30 — a full hour riding on one ambiguous wall clock.
Every example on this page is executed against the same engine that powers the tool, on every build.
Gotchas worth knowing
London to Sydney is 11, 10 and 9 hours — in one year
On 2026-01-15 a 12:00 London call reaches Sydney at 23:00, eleven hours later. By 2026-04-01 the gap is ten hours, and on 2026-07-15 it is nine — 12:00 in London lands at 21:00 in Sydney. Both cities move their clocks between those dates, in opposite directions, so check the pair on the meeting's own date every time.
The day badge can reach plus two
At 23:30 on Friday 2026-08-07 in Pago Pago it is already 00:30 on Sunday 2026-08-09 in Kiritimati — a 25-hour gap between UTC-11:00 and UTC+14:00 with no daylight saving involved. The badge counts calendar dates, and across the date line two is a real answer.
City search is honest about IANA names
The picker searches the zone identifiers themselves, so "mumbai" finds nothing — the database's Indian zone is Asia/Kolkata, one set of rules for the whole country. Pick the identifier whose rules your city follows. A restored link carrying a legacy spelling such as Asia/Calcutta still converts; the picker simply offers the modern name.
Future dates use the rules known today
For a 2030 meeting the conversion applies the transition calendar currently published — no tool can do better, because offsets are set by legislation and governments do change them. Treat far-future results as projections and re-check anything booked months ahead.
Dates run from 1900 to 2100
A date outside that window is refused with a message naming the bounds, instead of returning a number built on thin rule data. Inside the window the calendar is enforced too: 2028-02-29 converts, 2027-02-29 is refused as an impossible date.
Common errors
Source zone "America/NewYork" is not a known IANA timezone — pick a zone from the list, like "Europe/London" or "UTC".- Zone identifiers must exist in the IANA database. The message names which role failed — Source, Target or a numbered planner row — and echoes the identifier, so the missing underscore here is visible at a glance.
Date "1899-12-31" is outside the 1900–2100 window this tool converts.- The refusal states the supported window rather than extrapolating offsets the rule data cannot back. Pick a date inside the window; the inputs are kept exactly as you left them.
02:30 on 2026-03-08 does not exist in America/New_York — clocks jump forward from 2026-03-08 02:00 to 2026-03-08 03:00, skipping that span. Showing 03:30 on 2026-03-08, the requested time shifted past the gap.- A spring-forward warning, not an error: the conversion proceeds with the requested time moved past the skipped span, and both real alternatives are listed underneath so you can take the earlier side instead.
01:30 on 2026-11-01 happens twice in America/New_York — first at UTC-04:00, again at UTC-05:00 once clocks fall back. Showing the earlier occurrence (UTC-04:00).- A fall-back warning: one wall clock names two instants an hour apart. The earlier occurrence is used by default, and the later one is a single click away in the candidate list.
FAQ
Why is the hour difference between two cities different on another date?
Because each zone's daylight-saving calendar is set independently. When only one side of the pair has switched, the gap grows or shrinks by an hour — and for a pair like London and Sydney, which switch in opposite seasons, three different gaps occur across a single year. The difference sentence on this page is computed from the date in the request, so it already reflects whichever rules apply that day.
What does the +1 day badge mean when I book the meeting?
That attendee's calendar date is not yours. A 16:00 Thursday call in London is already 03:00 Friday in Sydney, so an invite that just says "Thursday" is wrong for Sydney. Put each city's own date on the invite — the badge exists so the most common cross-zone booking mistake is visible before you send anything.
Why does it say my chosen time does not exist, or happens twice?
You landed on the source zone's transition day. When clocks jump forward, the skipped span never occurs — 02:30 on 2026-03-08 in New York is such a time — and when they fall back, one span repeats at two different offsets. The warning prints the skipped or repeated span and the applied choice, and both candidate instants are listed with their offsets so you can re-run with the one you meant.
How does the share link store the meeting?
The date, time and zone list are folded into the fragment after the # in the URL. A fragment is processed by the receiving browser and is not sent as part of the HTTP request, and this page builds and reads it locally — sharing happens only when you actually hand the link to someone. Prefer a file? A state download saves the same meeting as a .json file instead of a link.
Why can't I enter EST or IST as a zone?
Those labels do not pin down a place or a season. IST is used for Indian, Israeli and Irish time; EST names only the winter half of the North American East's year. An IANA identifier carries the full year of rules, which is what a date-dependent conversion needs — and every result row prints the numeric UTC offset that actually applied, so no abbreviation is missed.
My city isn't in the list — which zone do I pick?
Pick the identifier whose rules your city follows; the database names one representative city per rule region, not every settlement. Mumbai keeps the same clock as Kolkata, so Asia/Kolkata is the correct choice — search finds it by the city segment or the full identifier, and the rules are identical either way.
Keyboard shortcuts
- ⌘/Ctrl + Enter
- Re-run the conversion for the current request.
- ⌘/Ctrl + S
- Download the readings and difference sentence as a .txt file.
- ⌘/Ctrl + C
- Copy the readings table as text when nothing is selected.
- ⌘/Ctrl + Shift + C
- Copy the readings table even while a selection exists.
- s
- Swap the source and target zones and convert again.
- t
- Cycle the color theme; single-key guards keep typing safe.
- ? or ⌘/Ctrl + /
- Open the shortcut help panel.
- Esc
- Dismiss the topmost dialog; inputs are never cleared.