MT to ART Time Converter
ART is 3 hours ahead of MT. The US Mountain states are currently on MDT (UTC-6:00), and ART is UTC-3:00.
Best Time to Call Between MT and ART
Both zones are inside normal business hours between 9:00 AM and 2:00 PM MT — that's 12:00 PM to 5:00 PM ART. That's a 5-hour window.
both at work MT only ART only neither — hours along the strip are MT.
Common Times Converted
MT on the left, ART on the right.
MT to ART: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| MT | ART | Working hours |
|---|---|---|
| 12:00 AM | 3:00 AM | — |
| 1:00 AM | 4:00 AM | — |
| 2:00 AM | 5:00 AM | — |
| 3:00 AM | 6:00 AM | — |
| 4:00 AM | 7:00 AM | — |
| 5:00 AM | 8:00 AM | — |
| 6:00 AM | 9:00 AM | ART only |
| 7:00 AM | 10:00 AM | ART only |
| 8:00 AM | 11:00 AM | ART only |
| 9:00 AM | 12:00 PM | Both zones |
| 10:00 AM | 1:00 PM | Both zones |
| 11:00 AM | 2:00 PM | Both zones |
| 12:00 PM | 3:00 PM | Both zones |
| 1:00 PM | 4:00 PM | Both zones |
| 2:00 PM | 5:00 PM | MT only |
| 3:00 PM | 6:00 PM | MT only |
| 4:00 PM | 7:00 PM | MT only |
| 5:00 PM | 8:00 PM | — |
| 6:00 PM | 9:00 PM | — |
| 7:00 PM | 10:00 PM | — |
| 8:00 PM | 11:00 PM | — |
| 9:00 PM | 12:00 AM next day | — |
| 10:00 PM | 1:00 AM next day | — |
| 11:00 PM | 2:00 AM next day | — |
What MT and ART Actually Are
MT — Mountain Time
Denver, Salt Lake City, Calgary, Edmonton — and Phoenix, which does not change its clocks. Standing at UTC-7:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to MST.
Mountain Time contains the most conspicuous daylight saving exception in North America: Arizona, which has opted out since 1968.
ART — Argentina Time
Buenos Aires, Córdoba, Rosario. Standing at UTC-3:00 as written, and the region does not change its clocks, so that offset holds all year. Argentina does not observe daylight saving, so this offset is fixed year-round.
Argentina has changed its time zone rules more than a dozen times since 1930 and abandoned daylight saving in 2009.
What This Means in Practice
This gap is not fixed
MT changes its clocks and ART does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, November 1, 2026 unless someone resets it.
Major Cities in Each Zone
Cities on MT
Cities on ART
Frequently Asked Questions
What is the time difference between MT and ART?
ART is 3 hours ahead of MT. That is the live figure. Taken strictly as written, the gap between MT and ART is 4 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM MT in ART?
9:00 AM MT is 12:00 PM ART.
What are the best hours to schedule a call between MT and ART?
Between 9:00 AM and 2:00 PM MT, which is 12:00 PM to 5:00 PM ART. Both sides are inside normal business hours through that window.
Does the difference between MT and ART change during the year?
Yes. MT observes daylight saving and ART does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, November 1, 2026.
Does ART always mean Argentina Time?
Argentina does not observe daylight saving, so this offset is fixed year-round.