Time Zone Converter
Free time zone converter — pick a date, time and two cities and get the exact local time in the other zone. Daylight saving handled automatically. Runs in your browser.
Pick a date, a time (24-hour HH:MM), and the two zones. The
converter returns the same instant expressed as local time in the target
zone, and tells you when the calendar day shifts.
How time zones and DST work
Every zone is an offset from UTC (Coordinated Universal Time). São Paulo is UTC-3, Tokyo is UTC+9, so when it’s noon in São Paulo it’s midnight (the next day) in Tokyo — a 12-hour gap.
The catch is daylight saving time. Many zones shift their clocks forward an hour in summer, so the offset isn’t fixed. New York is UTC-5 in winter (EST) and UTC-4 in summer (EDT). That’s why this tool asks for a date: the same wall-clock time converts differently in January than in July. The math here leans entirely on the browser’s built-in IANA time-zone database, which encodes every zone’s DST rules — so you never type an offset and the answer is right across DST boundaries.
Common conversions
These are fixed pairs that don’t move within the year on either side (Brazil and Japan have no DST; UTC never changes):
| From | To | Offset | Example |
|---|---|---|---|
| Brasília (BRT) | UTC | +3 h | 12:00 → 15:00 |
| UTC | Brasília (BRT) | −3 h | 15:00 → 12:00 |
| UTC | Tokyo (JST) | +9 h | 00:00 → 09:00 |
| Tokyo (JST) | UTC | −9 h | 09:00 → 00:00 |
These pairs do move with US daylight saving, so the gap depends on the date:
| From | To | Winter (EST) | Summer (EDT) |
|---|---|---|---|
| Brasília (BRT) | New York | −2 h | −1 h |
| New York | Brasília (BRT) | +2 h | +1 h |
In January, New York is two hours behind Brasília; in July, only one — because the US springs forward but Brazil doesn’t.
Worked examples
Noon in São Paulo, in UTC. Brasília is a fixed UTC-3, so add three hours:
12:00 in São Paulo → 15:00 UTC, same day.
10 PM in Los Angeles, in Tokyo. In July, Los Angeles is UTC-7 (PDT) and Tokyo is UTC+9 — a 16-hour jump forward:
22:00 Tuesday in Los Angeles → 05:00 UTC → 14:00 in Tokyo, the next day (+1 day).
6 AM in Tokyo, in Los Angeles. Going the other way crosses back over midnight:
06:00 in Tokyo → 21:00 UTC the day before → 14:00 in Los Angeles, the previous day (−1 day).
A note on Brazil
Brazil dropped daylight saving in 2019, so Brasília time is a steady UTC-3 year-round. If you’re coordinating between Brazil and the US or Europe, remember that the other side may still spring forward — the gap you memorised in July is an hour different in January.
Worked examples
-
Noon in São Paulo, in UTC
12:00 in America/Sao_Paulo = 15:00 in UTC on 2026-06-11
-
10 PM in Los Angeles is tomorrow in Tokyo
22:00 in America/Los_Angeles = 14:00 in Asia/Tokyo on 2026-07-16 (+1 day)
-
6 AM in Tokyo is the previous day in Los Angeles
06:00 in Asia/Tokyo = 14:00 in America/Los_Angeles on 2026-07-14 (−1 day)
Frequently asked questions
How does daylight saving time affect the result?
It's handled automatically. The converter uses your browser's built-in IANA time-zone database, which knows exactly when each zone starts and ends daylight saving. New York is UTC-5 in January (EST) but UTC-4 in July (EDT), so the same 9:00 AM converts to a different UTC time depending on the date — which is why you pick a date, not just a time. You never enter offsets yourself.
Why do I have to choose a date?
Because the offset between two zones can change across the year. Without a date, "3 PM New York to London" is ambiguous: during the few weeks each spring and autumn when the two regions switch clocks on different days, the gap is 4 hours instead of the usual 5. Picking the actual date removes the ambiguity.
What does \"+1 day\" or \"−1 day\" mean?
It means the converted time lands on a different calendar day. 10 PM Monday in Los Angeles is 2 PM Tuesday in Tokyo, so the result shows "+1 day". A westward jump can land you on the previous day ("−1 day"). The date shown is always the correct local date in the target zone.
Does Brazil use daylight saving time?
No. Brazil abolished daylight saving (horário de verão) in 2019. Brasília time (America/Sao_Paulo) is now a fixed UTC-3 all year, which makes Brazil↔UTC and Brazil↔US conversions simpler than they used to be — the offset no longer shifts between October and February.
Is this accurate for past and future dates?
For practical ranges, yes. The IANA database includes historical rule changes and the current rules projected forward. Far-future dates assume today's rules stay in place; if a government changes its time-zone policy later, a browser update refreshes the data. For everyday scheduling — meetings, calls, flights within a year or two — it's accurate.
Why use IANA zone names like America/Sao_Paulo instead of BRT or EST?
Abbreviations like CST are ambiguous (Central Standard Time in the US, China Standard Time, and Cuba Standard Time all share it), and EST/EDT change with the season. IANA identifiers like America/New_York name a place whose full DST history is known, so they're unambiguous and always resolve to the correct offset for any date.
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