PET to MST Time Converter
MST is 1 hour behind PET. PET is UTC-5:00, and The US Mountain states are currently on MDT (UTC-6:00).
Best Time to Call Between PET and MST
Both zones are inside normal business hours between 10:00 AM and 5:00 PM PET — that's 9:00 AM to 4:00 PM MST. That's a 7-hour window.
both at work PET only MST only neither — hours along the strip are PET.
Common Times Converted
PET on the left, MST on the right.
PET to MST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| PET | MST | Working hours |
|---|---|---|
| 12:00 AM | 11:00 PM prev day | — |
| 1:00 AM | 12:00 AM | — |
| 2:00 AM | 1:00 AM | — |
| 3:00 AM | 2:00 AM | — |
| 4:00 AM | 3:00 AM | — |
| 5:00 AM | 4:00 AM | — |
| 6:00 AM | 5:00 AM | — |
| 7:00 AM | 6:00 AM | — |
| 8:00 AM | 7:00 AM | — |
| 9:00 AM | 8:00 AM | PET only |
| 10:00 AM | 9:00 AM | Both zones |
| 11:00 AM | 10:00 AM | Both zones |
| 12:00 PM | 11:00 AM | Both zones |
| 1:00 PM | 12:00 PM | Both zones |
| 2:00 PM | 1:00 PM | Both zones |
| 3:00 PM | 2:00 PM | Both zones |
| 4:00 PM | 3:00 PM | Both zones |
| 5:00 PM | 4:00 PM | MST only |
| 6:00 PM | 5:00 PM | — |
| 7:00 PM | 6:00 PM | — |
| 8:00 PM | 7:00 PM | — |
| 9:00 PM | 8:00 PM | — |
| 10:00 PM | 9:00 PM | — |
| 11:00 PM | 10:00 PM | — |
What PET and MST Actually Are
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.
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.
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 PET
Cities on MST
Frequently Asked Questions
What is the time difference between PET and MST?
MST is 1 hour behind PET. That is the live figure. Taken strictly as written, the gap between PET and MST is 2 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM PET in MST?
9:00 AM PET is 8:00 AM MST.
What are the best hours to schedule a call between PET and MST?
Between 10:00 AM and 5:00 PM PET, which is 9:00 AM to 4:00 PM MST. Both sides are inside normal business hours through that window.
Does the difference between PET and MST 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.