Compare BST vs MST
See the current time difference between BST and MST, check DST changes, and find the best hours to schedule meetings.
How to Find the Time Difference Between BST and MST
Open the BST vs MST converter page: Go to https://www.xconvert.com/time-converter/bst-vs-mst to open the visual comparison grid with BST and MST already loaded as rows. This page is useful when you are scheduling a call between the UK and North American Mountain Time locations such as Arizona, or when a remote team in Britain needs to coordinate with logistics, support, or engineering staff working on Mountain Time.
Add relevant comparison cities with the “+ Add City” button: Click “+ Add City” and search for cities such as London, Phoenix, and Denver to see how BST compares with real business hubs that people actually use in scheduling. London is the main reference point for BST, Phoenix is important because Arizona stays on Mountain Standard Time year-round, and Denver is useful for checking how U.S. daylight saving changes can create different results from true MST during part of the year.
Drag across the grid to select a meeting window: Click “Select” if needed, then drag across the BST row to highlight a range such as 9:00 AM to 11:00 AM BST; the purple selection will show the matching time in MST as 2:00 AM to 4:00 AM MST, because BST is 7 hours ahead of MST. You can drag the center of the purple block to test other options or resize it with the left and right handles, which is especially useful for finding a time that works for a UK sales team and an Arizona operations team without forcing one side into overnight hours.
Export and share the selected time range: Once a range is selected, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link depending on how you coordinate meetings. For example, you can send an ICS file to a distributed team so the event appears in each person’s local time automatically, use Google Calendar for a recurring vendor call, or copy the share link into Slack or email so everyone sees the same BST-to-MST overlap.
BST vs MST Offset Explained
BST (British Summer Time) is UTC+1, while MST (Mountain Standard Time) is UTC-7, so the exact difference is 8 hours when comparing the named UTC offsets directly. In practical scheduling, that means 12:00 PM BST = 4:00 AM MST, and 6:00 PM BST = 10:00 AM MST. This large gap matters for customer support coverage, software deployment windows, and cross-border meetings between the UK and western North America.
The biggest source of confusion is that BST is itself a daylight saving time, not the UK’s winter standard time. The UK switches to BST on the last Sunday in March and returns to GMT (UTC+0) on the last Sunday in October. In 2025, the UK moves to BST on 30 March 2025 and back to GMT on 26 October 2025, so any BST-based comparison only applies during that summer period.
MST refers specifically to Mountain Standard Time, UTC-7, and is used year-round in places such as most of Arizona, including Phoenix (metro population about 5 million), except for the Navajo Nation, which observes daylight saving time. Many U.S. Mountain Time locations such as Denver, Colorado do not stay on MST all year; they switch to MDT (Mountain Daylight Time, UTC-6) from the second Sunday in March to the first Sunday in November. In 2025, that U.S. DST period runs from 9 March 2025 to 2 November 2025.
Because of those rules, the time gap depends on what you actually mean by “MST.” If you mean true MST (UTC-7), then BST is 8 hours ahead of MST for the entire BST season. But if you are really comparing BST with a U.S. city like Denver during summer, the city is on MDT (UTC-6), so BST is only 7 hours ahead of Denver during that period.
This distinction affects real scheduling decisions. A 9:00 AM BST meeting is 1:00 AM in Phoenix if you are comparing to true MST, which is usually too early for normal business calls, but 2:00 AM in Denver if Denver is on MDT, which is still impractical. A more realistic overlap for UK–Arizona coordination is often 4:00 PM to 6:00 PM BST, which corresponds to 8:00 AM to 10:00 AM MST, a workable window for SaaS support teams, freight coordination, legal reviews, and supplier calls.
Industries that commonly need BST–MST conversion include aviation, software, e-commerce, mining, and customer support. UK firms may coordinate with Arizona-based semiconductor, data center, or logistics partners, while travel planners often check the difference for flights routed through Phoenix Sky Harbor International Airport or connections onward to the U.S. Southwest. The offset also matters for financial communication because UK office hours overlap only partially with North American morning operations.
Frequently Asked Questions
What is the exact time difference between BST and MST?
BST is 8 hours ahead of MST when MST is used in its strict meaning of UTC-7. For example, when it is 3:00 PM in BST, it is 7:00 AM in MST. This applies cleanly when comparing BST with places that remain on Mountain Standard Time all year, such as most of Arizona.
Is BST always 8 hours ahead of Mountain Time in the United States?
No, because many U.S. Mountain Time locations do not stay on MST year-round. Cities such as Denver, Salt Lake City, and Albuquerque observe daylight saving time and switch to MDT (UTC-6) in summer, which makes BST only 7 hours ahead of them during that period. This is why it is important to compare BST with a specific city, not just a broad U.S. time-zone label.
Why does BST vs MST sometimes seem different on scheduling apps?
Many apps automatically convert based on a city’s current local rule rather than the label you typed. If you enter London and Denver in July, the app will usually compare BST (UTC+1) with MDT (UTC-6), not MST, so you will see a 7-hour gap instead of 8 hours. This causes confusion for users who expect “Mountain Time” and “MST” to mean the same thing in every season.
When does BST start and end each year?
BST starts on the last Sunday in March and ends on the last Sunday in October. In 2025, BST begins on 30 March 2025 and ends on 26 October 2025. Outside those dates, the UK uses GMT (UTC+0), so the UK-to-MST difference changes from 8 hours during BST to 7 hours during GMT.
Which places use MST all year instead of switching to daylight saving time?
The best-known example is most of Arizona, including Phoenix, one of the largest metro areas in the U.S. with roughly 5 million residents. Arizona remains on MST (UTC-7) throughout the year, except for the Navajo Nation, which follows daylight saving time. This makes Arizona a reliable reference if you need a stable BST-to-MST comparison for recurring meetings.
What is a good meeting time for teams working in BST and MST?
A practical overlap is usually 4:00 PM to 6:00 PM BST, which corresponds to 8:00 AM to 10:00 AM MST. That window works well for UK-based teams starting late afternoon coordination and Arizona-based teams beginning their workday, especially in software support, supply chain management, and client onboarding. Earlier UK morning slots usually fall in the middle of the night in MST.
How do I avoid mistakes when scheduling BST to MST calls?
Use a city-based comparison and check the date before sending invites, especially around March, October, and November, when DST transitions happen in the UK and the U.S. on different dates. On the xconvert grid, selecting a specific day with the date picker and comparing London with Phoenix or Denver will show whether your intended contact is on BST, MST, or MDT. Exporting the result as ICS or Google Calendar also reduces manual conversion errors because recipients see the event in their own local time.