Boulder, CO to Rio de Janeiro: time difference
Rio de Janeiro is 3 h ahead of Boulder, CO. Live clocks for both, the working hours they share, and how each one sits against your own time.
+3 h
Your time
One day, 2 clocks
Drag along the band to read any hour in every place at once.
Boulder, CO 08:20 8:20 AM Rio de Janeiro 11:20 11:20 AM You –:–
08:20 8:20 AM
Mountain Daylight Time · UTC-6
☀️ 07:19 · 🌙 18:17
11:20 11:20 AM
Brasilia Standard Time · UTC-3
☀️ 05:17 · 🌙 18:00
·
+3 h
Rio de Janeiro is 3 h ahead of Boulder, CO.
When you, Boulder, CO and Rio de Janeiro are all at the desk
Pick the working hours below – the window every location shares appears once your time zone is known.
Working hours
🇺🇸 Boulder, CO
0 12 AM 1 1 AM 2 2 AM 3 3 AM 4 4 AM 5 5 AM 6 6 AM 7 7 AM 8 8 AM 9 9 AM 10 10 AM 11 11 AM 12 12 PM 13 1 PM 14 2 PM 15 3 PM 16 4 PM 17 5 PM 18 6 PM 19 7 PM 20 8 PM 21 9 PM 22 10 PM 23 11 PM
🇧🇷 Rio de Janeiro
3 3 AM 4 4 AM 5 5 AM 6 6 AM 7 7 AM 8 8 AM 9 9 AM 10 10 AM 11 11 AM 12 12 PM 13 1 PM 14 2 PM 15 3 PM 16 4 PM 17 5 PM 18 6 PM 19 7 PM 20 8 PM 21 9 PM 22 10 PM 23 11 PM 0 12 AM 1 1 AM 2 2 AM
📍 Your time
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- Early
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Time zones side by side
| Detail | 🇺🇸 Boulder, CO | 🇧🇷 Rio de Janeiro |
|---|---|---|
| Local time | 08:20 | 11:20 |
| Local date | Tuesday, October 20, 2026 | Tuesday, October 20, 2026 |
| Time zone | Mountain Daylight Time | Brasilia Standard Time |
| UTC offset | UTC-6 | UTC-3 |
| Offset from Boulder, CO | — | +3 h |
| IANA zone | America/Denver | America/Sao Paulo |
| Daylight saving | On summer time → UTC-7, Nov 1, 01:00 | Not observed |
| Sunrise | 07:19 | 05:17 |
| Sunset | 18:17 | 18:00 |
| Daylight | 10 h 58 min | 12 h 43 min |
| People on this clock | 106,803 | 6,211,223 |
Compare Boulder, CO with another city
More comparisons with Boulder, CO: the time zones next to it and the far side of the clock.
Nearby time zones
Big time differences
Boulder, CO and Rio de Janeiro: common questions
How many hours ahead of Boulder, CO, is Rio de Janeiro?
The clocks in Rio de Janeiro are 3 hours ahead of those in Boulder (UTC−3 and UTC−6).
What time is it in Rio de Janeiro at the start of the working day in Boulder, CO?
The working day in Boulder starts at 9:00 AM; in Rio de Janeiro it is 12:00 PM at that moment.
What time is it in Rio de Janeiro at the end of the working day in Boulder, CO?
The working day in Boulder ends at 6:00 PM; in Rio de Janeiro it is 9:00 PM at that moment.
When do working hours in Boulder, CO, and in Rio de Janeiro overlap?
Working hours (9:00 AM–6:00 PM) overlap from 9:00 AM to 3:00 PM in Boulder, which is 12:00 PM to 6:00 PM in Rio de Janeiro.
When is it already the next day in Rio de Janeiro?
From 9:00 PM in Boulder, CO, it is already the next day in Rio de Janeiro. The other way round, until 3:00 AM in Rio de Janeiro it is still the previous day in Boulder.
Does the time gap between Boulder, CO, and Rio de Janeiro change during the year?
Yes – daylight saving time is used in Boulder but not in Rio de Janeiro. From November 1, 2026, Rio de Janeiro will be 4 hours ahead of Boulder.
