In the graph below you see the time zone difference between British Summer Time and Mountain Daylight Time. Drag the bubble to adjust the time and to see the corresponding time in the other time zone.
British Summer Time is the time zone of the United Kingdom when observing daylight saving time in the summer, including cities like London, Dublin and Glasgow. Mountain Daylight Time is the time zone of the US and Canadian states around the Rocky Mountains, with places like Edmonton, Calgary, Denver and Salt Lake City.
Usually it is preferable to schedule meetings in the late afternoon for the person in BST and before lunch for the person in MDT.
British Summer Time, or sometimes called British Standard Time, is the timezone of the United Kingdom in the summer months. It does not have a typical counterpart like most summer/winter pairs but is an exception to adjust for the dark winters in the UK!
United Kingdom only, including the Isle Of Man
All cities in the United Kingdom (England, Scotland, Wales and Northern Ireland), such as London, Manchester, Edinburgh, Cardiff and so on.
BST is the summer time equivalent of GMT. So for half the year the UK is on Greenwich Standard Time and the rest of the year they observe British Summer Time which is one hour ahead.
While GMT is observed in many places in addition to the UK BST is only observed in Britain (as the name suggests). Not even Ireland are on BST in the summer, instead they have their own time zone for this.
MDT is observed in the Western part of central US and Canada, as well as the North West corner of Mexico. It is 6 hours behind UTC and turns into MST in the summer. In Mexico, this time zone is known as Zona Pacifico (Pacific Zone). The name Mountain Daylight Time comes from it covering the Rocky Mountains in Western United States.
In the US, Arizona, Colorado, Montana, Utah, New Mexico and Wyoming are all observing Mountain Daylight Time but there is also a bunch where part of the state observe MDT and part another time zone, like CDT or PDT.
MDT is observed in parts of Canada, the US and Mexico. The only province in Canada to be fully covered by MDT is Alberta whereas other provinces like British Columbia and Northwest Territories are split between MDT and PDT.
In Mexico, it is only the states in the north western corner of the country, including Baja California, Sinaloa and Chihuahua that observe MDT.
The largest city observing Mountain Daylight Time is Phoenix, followed by Denver and El Paso/Juarez.
MDT is observed in almost all locations that observe Mountain Time, except the states of Arizona (US) and Sinaloa (Mexico). DST is in effect between March and November and adds one hour time difference to UTC.