Rio de Janeiro to Boulder, CO: time difference
Boulder, CO is 3 h behind Rio de Janeiro. Live clocks for both, the working hours they share, and how each one sits against your own time.
Your time
One day, 2 clocks
Drag along the band to read any hour in every place at once.
Rio de Janeiro 15:37 3:37 PM Boulder, CO 12:37 12:37 PM You –:–
15:37 3:37 PM
Brasilia Standard Time · UTC-3
☀️ 05:17 · 🌙 18:00
12:37 12:37 PM
Mountain Daylight Time · UTC-6
☀️ 07:19 · 🌙 18:17
·
−3 h
Boulder, CO is 3 h behind Rio de Janeiro.
When you, Rio de Janeiro and Boulder, CO are all at the desk
Pick the working hours below – the window every location shares appears once your time zone is known.
Working hours
🇧🇷 Rio de Janeiro
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
🇺🇸 Boulder, CO
21 9 PM 22 10 PM 23 11 PM 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
📍 Your time
- Asleep
- Early
- Working hours
- Evening
- Both working
- Right now
Time zones side by side
| Detail | 🇧🇷 Rio de Janeiro | 🇺🇸 Boulder, CO |
|---|---|---|
| Local time | 15:37 | 12:37 |
| Local date | Tuesday, October 20, 2026 | Tuesday, October 20, 2026 |
| Time zone | Brasilia Standard Time | Mountain Daylight Time |
| UTC offset | UTC-3 | UTC-6 |
| Offset from Rio de Janeiro | — | −3 h |
| IANA zone | America/Sao Paulo | America/Denver |
| Daylight saving | Not observed | On summer time → UTC-7, Nov 1, 01:00 |
| Sunrise | 05:17 | 07:19 |
| Sunset | 18:00 | 18:17 |
| Daylight | 12 h 43 min | 10 h 58 min |
| People on this clock | 6,211,223 | 106,803 |
Compare Rio de Janeiro with another city
More comparisons with Rio de Janeiro: the time zones next to it and the far side of the clock.
Nearby time zones
Big time differences
Rio de Janeiro and Boulder, CO: common questions
How many hours behind Rio de Janeiro is Boulder, CO?
The clocks in Boulder are 3 hours behind those in Rio de Janeiro (UTC−6 and UTC−3).
What time is it in Boulder, CO, at the start of the working day in Rio de Janeiro?
The working day in Rio de Janeiro starts at 9:00 AM; in Boulder it is 6:00 AM at that moment.
If it is 6:00 PM in Rio de Janeiro, what time is it in Boulder, CO?
At 6:00 PM in Rio de Janeiro, clocks in Boulder show 3:00 PM.
When do working hours in Rio de Janeiro and in Boulder, CO, overlap?
Working hours (9:00 AM–6:00 PM) overlap from 12:00 PM to 6:00 PM in Rio de Janeiro, which is 9:00 AM to 3:00 PM in Boulder.
Until what time in Rio de Janeiro is it still yesterday in Boulder, CO?
Before 3:00 AM in Rio de Janeiro, the date in Boulder has not changed yet. From 9:00 PM in Boulder, it is already the next day in Rio de Janeiro.
Does the time difference between Rio de Janeiro and Boulder, CO, change?
Yes. The clocks change only in Boulder. From November 1, 2026, Boulder will be 4 hours behind Rio de Janeiro.
