Which zone this page means. MST is standard time only; MDT (UTC-6) applies from March to November. Arizona stays on MST all year. UTC never observes daylight saving. It is the reference all other offsets are given against.
MST is behind UTC by 6 hours today
On 19 August 2026, Mountain Standard Time is on MDT at UTC-06:00 and Coordinated Universal Time is on UTC at UTC+00:00. The gap between them is 6 hours, with UTC ahead. So 9:00 am in MST is 3:00 pm in UTC, and 5:00 pm in MST is 11:00 pm in UTC. Going the other way, see UTC to MST.
The gap is not constant, and that is the part that catches people out
Mountain Standard Time is currently observing daylight saving and changes next on 1 November 2026, when clocks go back an hour. Coordinated Universal Time does not observe daylight saving at all, so the whole of the seasonal change comes from the MST side: the gap moves by an hour twice a year even though nothing changes in Coordinated Universal Time.
When you can actually both be at work
Taking a working day as 9:00 am to 5:00 pm local at each end, there are 2 overlapping hours in a normal day. In MST that window runs from 9:00 am to 11:00 am, which is 3:00 pm to 5:00 pm in UTC. Anything outside it needs one side to start early or finish late.
Zone rules are set by legislation and change, sometimes at short notice. This page is built against tzdata 2026a, last reviewed 2026-08-18. Quarterly. Zone rules change by legislation, sometimes at short notice. Version and review date are shown on every zone page. The converter above reads your browser's own copy of the zone database, so if a rule has changed since this page was built the live answer follows the new rule.
Every convention used above — whether the start date counts, how month ends are clamped, which holidays close an office — is written out on the methodology page, including the daylight-saving rules behind the 6-hour gap above.