The time difference between the UK and the USA depends on two things: which US time zone you're dealing with, and whether DST is currently in effect — in either country.

US Time Zones at a Glance

The contiguous United States spans four main time zones: Eastern (EST/EDT), Central (CST/CDT), Mountain (MST/MDT), and Pacific (PST/PDT). In winter, these are UTC−5, UTC−6, UTC−7, and UTC−8 respectively. In summer (DST), they shift to UTC−4, UTC−5, UTC−6, and UTC−7.

UK vs US: The Full Matrix

In winter, the UK is on GMT (UTC+0). New York (EST) is 5 hours behind, Chicago (CST) is 6 hours behind, Denver (MST) is 7 hours behind, and Los Angeles (PST) is 8 hours behind.

In summer, the UK is on BST (UTC+1). New York (EDT) is 5 hours behind, Chicago (CDT) is 6 hours behind, Denver (MDT) is 7 hours behind, and Los Angeles (PDT) is 8 hours behind.

Interestingly, the UK–US difference stays the same during summer — because both the UK and US move their clocks forward by one hour around the same period. The UK shifts in late March; the US shifts in the second week of March. For roughly two weeks, the difference is one hour less than usual.

The Two-Week Window When UK–US Time Changes

Between early and late March, the US has already moved to summer time but the UK has not yet. During this window, UK–US differences are one hour smaller than the winter norm. A New York colleague who's normally 5 hours behind may only be 4 hours behind for those two weeks. The same happens in early November, when the US reverts before the UK does.

Quick Reference: London to New York

January: UK on GMT, NY on EST — NY is 5 hours behind. March (after US spring forward, before UK): UK on GMT, NY on EDT — NY is 4 hours behind. April–October: UK on BST, NY on EDT — NY is 5 hours behind. November (after US fall back, before UK): UK on BST, NY on EST — NY is 6 hours behind. December: UK on GMT, NY on EST — NY is 5 hours behind.

Best Meeting Times: UK and US East Coast

The most workable overlap window is 2pm–6pm UK time, which is 9am–1pm New York time. This works year-round and covers both standard and summer time. For the US West Coast, the overlap is tighter: 5pm–7pm UK time corresponds to 9am–11am Los Angeles time.

Wenya handles UK–US timezone scheduling automatically inside WhatsApp and iMessage. Try it at wenyawanna.ai