PST to MST

About Pacific Time

Pacific Time runs the length of the west coast, from British Columbia to the Mexican border. It sits at UTC−8 as PST for about four months of the year and at UTC−7 as PDT for the other eight, moving on the second Sunday in March and the first Sunday in November — dates set by US federal law that the Canadian Pacific provinces follow so the border stays on one clock.

Cities on this clock: Los Angeles, San Diego, San Jose, Seattle, Portland, Las Vegas, Vancouver.

About Mountain Time

Mountain Time is UTC−7 as MST and UTC−6 as MDT, on the same transition dates as the rest of the United States. Arizona is the exception worth knowing: almost all of it stays on MST all year, so for the eight months the rest of the zone is on MDT, Phoenix keeps the same clock as Los Angeles rather than Denver.

Cities on this clock: Denver, Salt Lake City, Calgary, Edmonton.

How the difference is worked out

Neither Pacific Time nor Mountain Time moves its clock relative to the other, so mountain time is 1 hour ahead of pacific time is a rule rather than a fact about one particular year. The hour-by-hour table above holds on every date. The one exception is a few hours on each transition day: the two zones do change their clocks, and not at the same instant, so the gap is briefly an hour off between one switching and the other.

With both zones on their own standard time — daylight saving not in force anywhere — Mountain Time is 1 hour ahead of Pacific Time. That figure never changes; everything else on this page follows from it plus whichever clocks have moved.

Every figure here comes from the IANA time zone database via your browser's own Intl engine, using the zone ids America/Los_Angeles and America/Denver. Nothing is looked up on a server and nothing about your visit is recorded.