MST to PET Time Converter
PET is 1 hour ahead of MST. The US Mountain states are currently on MDT (UTC-6:00), and PET is UTC-5:00.
Best Time to Call Between MST and PET
Both zones are inside normal business hours between 9:00 AM and 4:00 PM MST — that's 10:00 AM to 5:00 PM PET. That's a 7-hour window.
both at work MST only PET only neither — hours along the strip are MST.
Common Times Converted
MST on the left, PET on the right.
MST to PET: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| MST | PET | Working hours |
|---|---|---|
| 12:00 AM | 1:00 AM | — |
| 1:00 AM | 2:00 AM | — |
| 2:00 AM | 3:00 AM | — |
| 3:00 AM | 4:00 AM | — |
| 4:00 AM | 5:00 AM | — |
| 5:00 AM | 6:00 AM | — |
| 6:00 AM | 7:00 AM | — |
| 7:00 AM | 8:00 AM | — |
| 8:00 AM | 9:00 AM | PET only |
| 9:00 AM | 10:00 AM | Both zones |
| 10:00 AM | 11:00 AM | Both zones |
| 11:00 AM | 12:00 PM | Both zones |
| 12:00 PM | 1:00 PM | Both zones |
| 1:00 PM | 2:00 PM | Both zones |
| 2:00 PM | 3:00 PM | Both zones |
| 3:00 PM | 4:00 PM | Both zones |
| 4:00 PM | 5:00 PM | MST only |
| 5:00 PM | 6:00 PM | — |
| 6:00 PM | 7:00 PM | — |
| 7:00 PM | 8:00 PM | — |
| 8:00 PM | 9:00 PM | — |
| 9:00 PM | 10:00 PM | — |
| 10:00 PM | 11:00 PM | — |
| 11:00 PM | 12:00 AM next day | — |
What MST and PET Actually Are
MST — Mountain Standard Time
Denver, Salt Lake City, Calgary — and Phoenix year-round. 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. Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.
Arizona has stayed on MST year-round since 1968 — the Navajo Nation within it does observe daylight saving, making the state a patchwork.
PET — Peru Time
Lima, Arequipa, Trujillo. Standing at UTC-5:00 as written, and the region does not change its clocks, so that offset holds all year.
Peru sits at UTC-5 year-round despite spanning longitudes that would suggest otherwise, and has not used daylight saving since a short trial in the 1990s.
What This Means in Practice
This gap is not fixed
MST changes its clocks and PET 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.
Close enough to share a working day
At only 1 hour apart, the two working days overlap almost completely. Scheduling is barely constrained by the difference.
Major Cities in Each Zone
Cities on MST
Cities on PET
Frequently Asked Questions
What is the time difference between MST and PET?
PET is 1 hour ahead of MST. That is the live figure. Taken strictly as written, the gap between MST and PET is 2 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM MST in PET?
9:00 AM MST is 10:00 AM PET.
What are the best hours to schedule a call between MST and PET?
Between 9:00 AM and 4:00 PM MST, which is 10:00 AM to 5:00 PM PET. Both sides are inside normal business hours through that window.
Does the difference between MST and PET change during the year?
Yes. MST observes daylight saving and PET 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 MST always mean Mountain Standard Time?
Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.