How this time zone converter works
A time zone converter answers a deceptively simple question: when it is a certain time in one place, what time is it somewhere else? The tricky part is that the answer changes through the year, because many regions advance their clocks for daylight saving time and then fall back again. This converter sidesteps that complexity by working with IANA time-zone names like America/New_York or Asia/Tokyo rather than fixed offsets.
You provide a base time and a base time zone. The tool treats that as a single instant in time, then asks your browser's built-in Intl.DateTimeFormat to render the same instant in every comparison zone you have added. Because the formatting uses the IANA database, daylight saving transitions and even unusual 30- or 45-minute offsets are handled for you. Each row also shows a day offset — for example +1 day — when the converted time lands on a different calendar date than the base.
A quick reference
| Zone | IANA name | Note |
|---|---|---|
| UTC | UTC | Global reference, no daylight saving |
| London | Europe/London | UTC in winter, +1 in summer (BST) |
| New York (ET) | America/New_York | UTC−5 / −4 with DST |
| Tokyo | Asia/Tokyo | UTC+9, no daylight saving |
| Mumbai | Asia/Kolkata | UTC+5:30, a half-hour offset |
Reference note: conversions rely on the IANA time-zone database shipped with your browser and the device's current rules. For dates far in the past or future, offsets reflect the rules your browser knows about and may differ from political changes not yet captured.
Frequently asked questions
- What time is it in another city when it is a certain time here?
- Set the base time and base time zone to your local clock, then add the cities you care about. The table shows the matching local time in each city for that exact instant — so you can read off, for example, what 3 PM in New York is in Tokyo.
- How do I plan a meeting across time zones?
- Choose a candidate start time in one person's zone as the base, add the other participants' zones, and scan the table for a row where everyone is within working hours. Nudge the base time until the converted times suit all participants.
- Does this account for daylight saving time?
- Yes — conversions use your browser's built-in IANA time-zone database, so daylight saving transitions and historical offset rules are applied automatically for the chosen date.
- What is UTC?
- UTC (Coordinated Universal Time) is the global time standard from which all time zones are offset. It does not observe daylight saving time, which makes it a stable reference for scheduling and logging events worldwide.
- How many time zones are there?
- There are 24 standard one-hour zones, but in practice around 38 to 40 distinct UTC offsets are in use because some regions use 30- or 45-minute offsets and others shift for daylight saving time.
- Why is the date sometimes different?
- When two zones sit on opposite sides of the date line or far apart in offset, the same instant can fall on different calendar days. The table marks this with a day offset such as +1 day or −1 day.