timeinusa.net

MST to HST — Mountain to Hawaii Time

Hawaii is 3 hours behind Mountain in winter and 4 hours behind in summer.

The conversion rule

During standard time (November–March), subtract 3 hours from Mountain Time for Hawaii: 12:00 PM MST is 9:00 AM HST. Hawaii never adjusts its clocks, so once Denver switches to MDT the gap becomes 4 hours — noon MDT is 8:00 AM HST.

Winter offers 12:00–5:00 PM MT / 9:00 AM–2:00 PM HST; under MDT the shared block is 1:00–5:00 PM MT / 9:00 AM–1:00 PM HST. Afternoon in the Rockies is the reliable slot.

Curiously, Phoenix and Honolulu are the stable pair here: neither Arizona nor Hawaii observes DST, so they stay exactly 3 hours apart every day of the year.

MST to HST conversion chart

Mountain (MST)Hawaii (HST)
12:00 AM (midnight)9:00 PM (prev. day)
1:00 AM10:00 PM (prev. day)
2:00 AM11:00 PM (prev. day)
3:00 AM12:00 AM (midnight)
4:00 AM1:00 AM
5:00 AM2:00 AM
6:00 AM3:00 AM
7:00 AM4:00 AM
8:00 AM5:00 AM
9:00 AM6:00 AM
10:00 AM7:00 AM
11:00 AM8:00 AM
12:00 PM (noon)9:00 AM
1:00 PM10:00 AM
2:00 PM11:00 AM
3:00 PM12:00 PM (noon)
4:00 PM1:00 PM
5:00 PM2:00 PM
6:00 PM3:00 PM
7:00 PM4:00 PM
8:00 PM5:00 PM
9:00 PM6:00 PM
10:00 PM7:00 PM
11:00 PM8:00 PM

The table shows the 3-hour standard-time conversion, correct from the first Sunday of November to the second Sunday of March. While the Mountain zone is on MDT (Mar 8 – Nov 1 in 2026), subtract 4 hours. Against Arizona, 3 hours is always right.

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

Frequently asked questions

Why is Hawaii 3 hours behind Denver in January but 4 in July?

Hawaii sits on HST (UTC−10) with no daylight saving, while the Mountain zone alternates between MST (UTC−7) and MDT (UTC−6). The gap is 3 hours in the standard-time months and 4 hours under MDT.

What is 6:00 PM MST in Hawaii?

3:00 PM HST in winter; in summer 6:00 PM MDT is 2:00 PM HST.

Is the Phoenix–Honolulu difference also seasonal?

No. Arizona and Hawaii both skip daylight saving, so Phoenix is exactly 3 hours ahead of Honolulu all year.