What it solves
“Let’s meet at 9” means very different things in Seoul, London and San Francisco, and twice a year daylight saving quietly shifts the gaps. This converter takes one wall-clock time and lays it out for every city you care about, flagging when the date rolls over to the next or previous day.
How to use it
- Choose the time zone the meeting is set in (it starts with yours).
- Pick the date and time.
- Read the list of cities, remove the ones you don’t need, and add others by name. Copy the summary to paste into an invite.
How it works
- Time zone rules come from the IANA database built into modern browsers (
Intl.DateTimeFormat), the same data operating systems use. - Your local time is turned into an exact instant (UTC) using the offset valid on that date, then shown in each target zone.
- Skipped times (spring forward) and repeated times (fall back) are detected and explained instead of silently guessed.
Examples
Seoul to New York in summer
9:00 AM on July 1, 2026 in Seoul is 8:00 PM on June 30 in New York (EDT, UTC−4) — the previous evening.
The week the UK changes clocks
London is on UTC+0 until March 29, 2026, then UTC+1 (BST). A call at the same London time on March 28 and March 30 lands an hour apart for people in Asia.
India’s half-hour offset
Kolkata stays on UTC+5:30 all year, so it’s 4:30 or 5:30 hours ahead of London depending on British daylight saving.
Limitations
- Accuracy depends on your browser’s time zone data. Keep your browser updated when governments change their rules.
- Historical dates before modern standard time (around the early 1900s) may not reflect local practice.