Time difference between Denver and London

The gap is not the same all year

Every converter gives one number for this pair. That number is right for most of the year and wrong for part of it, because Denver goes forward on the second Sunday in March and back on the first Sunday in November and London goes forward on the last Sunday in March and back on the last Sunday in October.

Both change their clocks and both are in the northern hemisphere, but not on the same weekend — Denver goes forward on the second Sunday in March and London on the last Sunday in March. For the days in between, the gap is neither party's expected figure, and a standing meeting silently moves by an hour. That mismatch is a common cause of a missed international call.

About Denver and London

Denver is UTC−7 in winter, the US Mountain zone, and the smallest of the four continental US zones by population. Arizona, in the same zone, does not change its clocks, so for half the year Denver and Phoenix are an hour apart.

London is the reference the rest of the system is measured from: Greenwich sits inside the city, and UTC±0 is its winter time. It does not stay there — Britain moves to UTC+1 for seven months of the year, which is why "London is GMT" is wrong more often than it is right.

What 7 hours actually costs you

The window is 1 hour wide and that is all there is. 9:00 AM–10:00 AM in Denver is 4:00 PM–5:00 PM in London, and anything outside it puts somebody at their desk when they are not meant to be. A pair this tight is worth putting in a calendar rather than agreeing each time.

When they can both be at their desks

Nine-to-five in both cities overlaps for 1 hour — 9:00 AM to 10:00 AM in Denver, the same moment as 4:00 PM to 5:00 PM in London.

Denver

London

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How far apart Denver and London are

The shortest path over the Earth's surface between the two is 7,541 km (4,686 miles). Flown along that line, an airliner at cruising speed takes roughly 9 hours 35 minutes in the air — actual routings add to it, and whether a nonstop service exists depends on the airlines rather than the distance.

Over that distance you cross 7 hours of clock, which is where jet lag comes from: the body shifts by about an hour a day, so 7 hours takes most people 7 days or so to absorb. Flying east to London is the harder direction — you lose the hours and have to fall asleep earlier than your body wants.

Denver to London, hour by hour

On the usual gap of 7 hours.

Frequently asked questions