MST to HST Time Converter
HST is 4 hours behind MST. The US Mountain states are currently on MDT (UTC-6:00), and HST is UTC-10:00.
Best Time to Call Between MST and HST
Both zones are inside normal business hours between 1:00 PM and 5:00 PM MST — that's 9:00 AM to 1:00 PM HST. That's a 4-hour window.
both at work MST only HST only neither — hours along the strip are MST.
Common Times Converted
MST on the left, HST on the right.
MST to HST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| MST | HST | Working hours |
|---|---|---|
| 12:00 AM | 8:00 PM prev day | — |
| 1:00 AM | 9:00 PM prev day | — |
| 2:00 AM | 10:00 PM prev day | — |
| 3:00 AM | 11:00 PM prev day | — |
| 4:00 AM | 12:00 AM | — |
| 5:00 AM | 1:00 AM | — |
| 6:00 AM | 2:00 AM | — |
| 7:00 AM | 3:00 AM | — |
| 8:00 AM | 4:00 AM | — |
| 9:00 AM | 5:00 AM | MST only |
| 10:00 AM | 6:00 AM | MST only |
| 11:00 AM | 7:00 AM | MST only |
| 12:00 PM | 8:00 AM | MST only |
| 1:00 PM | 9:00 AM | Both zones |
| 2:00 PM | 10:00 AM | Both zones |
| 3:00 PM | 11:00 AM | Both zones |
| 4:00 PM | 12:00 PM | Both zones |
| 5:00 PM | 1:00 PM | HST only |
| 6:00 PM | 2:00 PM | HST only |
| 7:00 PM | 3:00 PM | HST only |
| 8:00 PM | 4:00 PM | HST only |
| 9:00 PM | 5:00 PM | — |
| 10:00 PM | 6:00 PM | — |
| 11:00 PM | 7:00 PM | — |
What MST and HST 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.
HST — Hawaii Standard Time
Honolulu and the rest of Hawaii. Standing at UTC-10:00 as written, and the region does not change its clocks, so that offset holds all year. Hawaii does not observe daylight saving, so this offset holds all year.
Hawaii dropped daylight saving in 1967 and never resumed it. Being close to the equator, its daylight barely varies across the year, so there is little to gain.
What This Means in Practice
This gap is not fixed
MST changes its clocks and HST 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 MST
Cities on HST
Frequently Asked Questions
What is the time difference between MST and HST?
HST is 4 hours behind MST. That is the live figure. Taken strictly as written, the gap between MST and HST is 3 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM MST in HST?
9:00 AM MST is 5:00 AM HST.
What are the best hours to schedule a call between MST and HST?
Between 1:00 PM and 5:00 PM MST, which is 9:00 AM to 1:00 PM HST. Both sides are inside normal business hours through that window.
Does the difference between MST and HST change during the year?
Yes. MST observes daylight saving and HST 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.
Does HST always mean Hawaii Standard Time?
Hawaii does not observe daylight saving, so this offset holds all year.