Date and time
Enter the source clock time and named zone, then compare each target on that exact date.
YYYY-MM-DDTHH:mm[:ss], or a space instead of T. No Z, offset or fractional seconds.
Use UTC or an IANA ID such as America/New_York. Changing the source reinterprets the same clock reading.
One ID per line; up to 20 physical lines and 2,000 characters. Blank lines are ignored; repeated IDs are deduplicated.
Enter a source time or load the example.
Dates are processed in this browser and are not sent to a server.
Engine: @js-temporal/polyfill 0.5.1 with this browser’s Intl data. The browser does not expose its time zone database version; future rules may change.
Detected browser time zone: Unavailable
Inputs changed. Recalculate before copying or downloading.
This time zone converter helps when a meeting time, deployment window or support handoff crosses regions. A remembered five-hour difference is unreliable during the weeks when countries change their clocks on different dates.
Keep the source calendar date alongside the clock reading. Every result refers to one UTC instant, even when the destination is already on another day.
The time zone converter keeps each target’s full date, clock reading and UTC offset together. A separate difference compares that target with the source, so UTC−05:00 is not mistaken for five hours behind every source city.
When New York repeats 01:30 on November 3, 2024, the input can mean 05:30Z or 06:30Z. The default rejects that ambiguity, shows both candidates and waits for your choice; it never silently treats the second occurrence as the first.
Use UTC for a UTC to local time task. Use the local-source shortcut only when the typed time belongs to your device’s configured zone. These shortcuts preview the change; they preserve the clock digits, not the previous instant.
First and second occurrence are available for an overlap. A spring-forward gap is an error under either choice. Use the displayed candidate UTC values and offsets to match the original event record.
Automatic conversion waits 350 ms after an edit. Switch it off to use Convert or Ctrl/Cmd + Enter. Edits disable export; Example, Clear and source shortcuts show a preview, while Undo restores the inputs and their result together.
IANA time zones supply date-specific transitions. New York at 09:00 on March 20, 2024 corresponds to 13:00 in London: a four-hour difference while their daylight saving time schedules are out of step.
Keep London, New York and Tokyo, or edit the list to compare other regions. The order follows your first occurrence of each ID, and one invalid target blocks the conversion with its physical line number.
UTC offset compares a destination with UTC. Difference from source compares the two local clocks at the resolved instant. The sign means destination minus source, and can exceed 24 hours across the date line.
Asia/Kathmandu uses a quarter-hour component; Australia/Lord_Howe can change by half an hour. Offsets and differences preserve seconds when supplied by historical data, rather than rounding every region to whole hours.
The date determines the applicable offset and daylight-saving rule. Two cities may be four hours apart in one week and five in another. Enter the actual event date instead of applying today’s difference to every future appointment.
You can enter up to 20 physical lines, with one UTC or named IANA zone per line. Blank lines are skipped and the same ID is kept once regardless of letter case. Different aliases are not automatically merged.
Yes, using the browser’s IANA data for the selected date. A repeated source time requires an explicit occurrence; a missing source time is rejected. An ordinary target conversion has no ambiguity because the UTC instant is already known.
Yes. The date-difference field compares calendar dates with the source. It can be negative, zero or positive. UTC−12 to UTC+14 can even produce a difference of two calendar days for the same instant.
The same abbreviation can identify different regions, and a fixed abbreviation may omit seasonal changes. Enter America/New_York, Asia/Shanghai or another supported regional ID rather than asking the tool to guess what CST or IST means.
A result needs a closer look?
Use the time zone converter with your event’s date, confirm the source zone and keep the UTC instant beside the local results when passing the report on.