timeinusa.net

HST to MST — Hawaii to Mountain Time

Mountain Time is 3 hours ahead of Hawaii in winter and 4 hours ahead in summer.

The conversion rule

While Denver is on standard time, add 3 hours to Hawaii Time: 12:00 PM HST is 3:00 PM MST. Hawaii stays put all year, so under MDT the offset is 4 hours — noon HST reads 4:00 PM in Denver.

Winter window: 9:00 AM–2:00 PM HST / 12:00–5:00 PM MT. Summer: 9:00 AM–1:00 PM HST / 1:00–5:00 PM MT. Island mornings, Rockies afternoons.

Phoenix is the exception that simplifies things: Arizona skips DST just like Hawaii, so Honolulu is 3 hours behind Phoenix every day of the year.

HST to MST conversion chart

Hawaii (HST)Mountain (MST)
12:00 AM (midnight)3:00 AM
1:00 AM4:00 AM
2:00 AM5:00 AM
3:00 AM6:00 AM
4:00 AM7:00 AM
5:00 AM8:00 AM
6:00 AM9:00 AM
7:00 AM10:00 AM
8:00 AM11:00 AM
9:00 AM12:00 PM (noon)
10:00 AM1:00 PM
11:00 AM2:00 PM
12:00 PM (noon)3:00 PM
1:00 PM4:00 PM
2:00 PM5:00 PM
3:00 PM6:00 PM
4:00 PM7:00 PM
5:00 PM8:00 PM
6:00 PM9:00 PM
7:00 PM10:00 PM
8:00 PM11:00 PM
9:00 PM12:00 AM (midnight, next day)
10:00 PM1:00 AM (next day)
11:00 PM2:00 AM (next day)

The rows use the 3-hour standard gap, valid November–March. During MDT — Mar 8 to Nov 1 in 2026 — add 4 hours. Against Arizona, adding 3 is always right.

Reverse direction: MST to HST (subtract 3 hours in winter, 4 in summer). Related: HST to EST, HST to CST, HST to PST.

Frequently asked questions

Is Denver always 3 hours ahead of Honolulu?

No — 3 hours only in winter. When Denver is on MDT the difference is 4 hours, because Hawaii keeps UTC−10 all year.

What about the Phoenix–Honolulu difference?

Fixed at 3 hours. Neither Arizona nor Hawaii observes daylight saving, so their clocks never drift against each other.

What is 11:00 AM HST in Mountain Time?

2:00 PM MST in winter, 3:00 PM MDT in summer.