Highlighted rows fall within 09:00–18:00 in both places: 6 shared working hours.
How many hours is MST ahead of HST?
As abbreviations, HST is always 3 hours behind of MST: MST is UTC−7 and HST is UTC−10. To convert, subtract 3 hours.
When the MST to HST time difference changes
For most of the year HST is 4 hours behind of MST. From 1 November to 31 December 2026, HST is 3 hours behind of MST instead, because the two places change their clocks on different dates. Meetings booked by the usual gap land an hour off in those weeks.
Dates
HST vs MST
Length
1 November 2026 to 31 December 2026
3 hours behind
61 days
1 January 2027 to 13 March 2027
3 hours behind
72 days
14 March 2027 to 6 November 2027
4 hours behind
238 days
7 November 2027 to 31 December 2027
3 hours behind
55 days
Best time for a meeting between MST and HST
When HST is 4 hours behind of MST: 4 shared office hours, 13:00 to 17:00 in MST (09:00 to 13:00 in HST).
When HST is 3 hours behind of MST: 5 shared office hours, 12:00 to 17:00 in MST (09:00 to 14:00 in HST).
Frequently asked questions about MST and HST time
How many hours ahead is HST of MST?
HST (UTC−10) is 3 hours behind of MST (UTC−7).
Does the time difference between MST and HST change?
Yes. It is usually 4 hours behind, but changes when one side moves its clocks: 3 hours behind from 1 November to 31 December 2026; 3 hours behind from 1 January to 13 March 2027.