To calculate a timezone difference, find each place's UTC offset on the date you care about and subtract one from the other. Brasília is UTC−3 all year; London is UTC+0 from October 25, 2026, so London is 3 hours ahead of Brasília.
The arithmetic is easy. Most mistakes come from daylight saving time, which shifts the gap by an hour a few times a year, and from date changes when the other city is far away.
What a UTC offset means
UTC (Coordinated Universal Time) is the world's reference clock. Every time zone is expressed as a number of hours ahead (+) or behind (−) UTC. Some offsets in effect right now:
- Brasília: UTC−3, with no daylight saving time since 2019.
- New York: UTC−4 until October 31, 2026, then UTC−5 from November 1, 2026.
- London and Lisbon: UTC+1 until October 24, 2026, then UTC+0 from October 25.
- Tokyo: UTC+9 year-round.
- India: UTC+5:30, a half-hour zone.
"Twenty-four one-hour zones" is only a rough picture. The IANA time zone database, which phones and computers rely on, lists close to 40 distinct offsets in use, from UTC−11 to UTC+14, including odd ones such as +5:45 (Nepal) and +3:30 (Iran). You can check the reference clock on the current UTC time page.
Step-by-step method
- Look up each location's offset for that specific date. Don't rely on memory; check whether either place is on daylight saving time that day.
- Subtract: destination offset minus origin offset. A positive result means the destination is ahead; a negative one means it is behind.
- Add the result to your local time. If you go past 24:00, it is the next day; below 00:00, the previous day.
If you'd rather skip the math, the time zone converter does it with the IANA database and handles each country's DST rules automatically.
Worked examples from Brasília
Brasília to New York in November
On November 3, 2026, New York is on UTC−5 and Brasília on UTC−3: −5 − (−3) = −2. A 3:00 PM call in Brasília is 1:00 PM in New York. Two weeks earlier, with New York still on UTC−4, the gap was only one hour. See the full Brazil to United States time difference.
Brasília to Tokyo: crossing midnight
Tokyo is UTC+9: +9 − (−3) = +12. At 9:00 PM on Monday in Brasília, it is already 9:00 AM on Tuesday in Tokyo. Whenever the sum goes beyond midnight, move the date forward.
Brasília to India: the half hour
India uses UTC+5:30: +5:30 − (−3) = +8:30. At 8:00 AM in Brasília, it is 4:30 PM in Mumbai or New Delhi. With fractional zones, do the math in minutes instead of rounding.
Reference table: Brasília vs. major cities
Calculated with the IANA time zone database (release 2026a). "Today" means October 17, 2026. A plus sign means the city is ahead of Brasília.
| City | Today (Oct 17) | From Oct 25 | From Nov 1 |
|---|---|---|---|
| Los Angeles | −4 h | −4 h | −5 h |
| Chicago | −2 h | −2 h | −3 h |
| New York and Toronto | −1 h | −1 h | −2 h |
| Mexico City | −3 h | −3 h | −3 h |
| Bogotá and Lima | −2 h | −2 h | −2 h |
| Buenos Aires and Santiago | 0 | 0 | 0 |
| Lisbon and London | +4 h | +3 h | +3 h |
| Madrid, Paris, Berlin and Rome | +5 h | +4 h | +4 h |
| Johannesburg | +5 h | +5 h | +5 h |
| Moscow | +6 h | +6 h | +6 h |
| Dubai | +7 h | +7 h | +7 h |
| Mumbai | +8:30 | +8:30 | +8:30 |
| Beijing | +11 h | +11 h | +11 h |
| Tokyo and Seoul | +12 h | +12 h | +12 h |
| Sydney | +14 h | +14 h | +14 h |
| Auckland | +16 h | +16 h | +16 h |
To see all of these clocks side by side right now, open the world time page.
Daylight saving time: why the gap changes
Because Brazil no longer changes its clocks, every shift in the difference comes from the other side. The dates that matter for late 2026 and early 2027:
- Europe: summer time ends on October 25, 2026, at 01:00 UTC (10:00 PM on October 24 in Brasília) and returns on March 28, 2027. More in the Europe daylight saving time guide.
- United States and Canada: clocks fall back on November 1, 2026, at 2:00 AM local time (3:00 AM in Brasília for the East Coast) and spring forward on March 14, 2027. See US daylight saving time.
- Southern Hemisphere: Chile (since September 6, 2026), New Zealand (since September 27) and southeastern Australia (since October 4) are on summer time until early April 2027. That is why Santiago matches Brasília today but falls one hour behind in the southern winter.
Common mistakes
- Using a memorized offset. "New York is UTC−5" is only true from November to March.
- Forgetting that the US and Europe switch on different dates. Between October 25 and 31, 2026, London is back on standard time but New York is not.
- Missing the date change when calling Asia or Oceania.
- Treating a country as one zone. The US, Russia, Australia and Brazil all have several; confirm the city.
- Rounding half-hour zones such as India, Iran and parts of Australia.
Frequently asked questions
What is the formula for a timezone difference?
Difference = destination UTC offset − origin UTC offset, both for the same date. From Brasília (UTC−3) to Paris in November (UTC+1): 1 − (−3) = 4 hours ahead.
Does Brazil observe daylight saving time in 2026?
No. Decree 9,772 of April 25, 2019 ended daylight saving time nationwide, and Brasília stays on UTC−3 all year.
Why does the gap between Brazil and the UK change in October?
The UK leaves summer time on October 25, 2026, so the gap drops from 4 to 3 hours. It goes back to 4 hours on March 28, 2027.
How do I handle results past midnight?
Subtract 24 hours and move one day forward. Example: 10:00 PM in Brasília plus 12 hours is 10:00 AM the next day in Tokyo.
Summary
Find both UTC offsets for the exact date, subtract, and adjust the day if you cross midnight. Brasília is fixed at UTC−3, so only the other side moves: Europe falls back on October 25, 2026, and North America on November 1, 2026. When in doubt, use a tool built on the IANA database.