SuperCalc

Time Zone Converter

See what time it is anywhere — or convert a specific moment across cities. DST-correct, half-hour-offset-aware, and instant.

Time across cities

Time Zone Converter

Click any hour to see what it lands on in every city. The first row's hours run 12am to 11pm — every other row is its local time at the same instant.

12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
5p
6p
7p
8p
9p
10p
11p
San Francisco
UTC -7anchor
New York
UTC -4
London
UTC +1
Mumbai
UTC +5:30
Tokyo
UTC +9
Right now
San Francisco
12:34 PM
Sat, May 9
New York
3:34 PM
Sat, May 9
London
8:34 PM
Sat, May 9
Mumbai
1:04 AM
Sun, May 10
Tokyo
4:34 AM
Sun, May 10
Quick reference

When it's this time in San Francisco:

San FranciscoNew YorkLondonMumbaiTokyo
6:00 AM9:00 AM2:00 PM6:30 PM10:00 PM
9:00 AM12:00 PM5:00 PM9:30 PM1:00 AM
12:00 PM3:00 PM8:00 PM12:30 AM4:00 AM
3:00 PM6:00 PM11:00 PM3:30 AM7:00 AM
6:00 PM9:00 PM2:00 AM6:30 AM10:00 AM
9:00 PM12:00 AM5:00 AM9:30 AM1:00 PM

How timezones really work

A timezone isn't a fixed UTC offset. It's a region that shares a set of rules — including DST transition dates, historical offset changes, and exceptions like India and Nepal's half-hour offsets. The IANA timezone database tracks every one of these rules across every region in the world.

When you pick "London", what you really mean is Europe/London. That id maps to a set of rules: GMT in winter, BST (UTC+1) in summer, with transition dates that change yearly per EU directive. Same idea for every city.

We never store an offset like "+5:30" — we store the IANA id and compute the offset fresh for each moment. That's why our results stay correct across DST switches, leap years, and future political changes (when a country changes its rules, the browser's tz database updates and we get the fix for free).

FAQ

Are timezone offsets correct, including DST and half-hour zones?
Yes. We use the IANA timezone database (the canonical source — same one Linux, macOS, and every JavaScript engine ship). DST transitions, half-hour offsets (India +5:30, Nepal +5:45, Newfoundland −3:30), and historical political changes are all handled automatically. Your browser updates the database with each release, so we don't have to ship updates ourselves.
Why use IANA timezones instead of GMT offsets like UTC+5?
GMT offsets change with DST and political decisions. "India" is always Asia/Kolkata, but "UTC+5" could be five different countries with five different DST rules. Storing the IANA id (Asia/Kolkata) means the converter gets the right offset for any specific date — including dates years ago or years from now, when DST rules might differ from today.
What do the time-of-day labels mean?
Each city shows a small status pill — Morning, Day, Evening, Late, Night, or Asleep — based on the local hour. They're a quick read on whether the city is awake or sleeping at the converted time. The weekend badge appears when the local date in that city falls on a Saturday or Sunday.
Why does the date sometimes show "Tue" while my source city is on Mon?
The international date line. When it's late Monday afternoon in San Francisco, it's already early Tuesday morning in Tokyo — same instant in time, different calendar dates. The tool always shows the correct local date for each city.
Can I just see what time it is right now everywhere?
Yes — that's the default. The page opens with "Use now" enabled, showing live current times across your selected cities. The display ticks every 30 seconds. Type a different time only if you want to convert a specific moment.
Where are my city selections saved?
Locally in your browser (localStorage). Nothing is sent to a server — the timezone math runs entirely client-side via the browser's IANA database.

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