EST vs GMT time zone comparison

How EST and GMT compare

Greenwich Mean Time runs five hours ahead of Eastern Standard Time during the northern winter, the most common transatlantic scheduling axis for businesses with a New York and London footprint. The five-hour gap holds from late October until mid-March. From late March until late October, the UK observes British Summer Time (BST, UTC+1) and the US observes Eastern Daylight Time (EDT, UTC-4), so the effective gap shrinks to four hours for most of the year. The pages on this site default to the current standard-time offset; check the date if you are scheduling across a DST transition. The classic overlap window is 1 PM to 5 PM GMT (8 AM to 12 PM EST), which catches the London afternoon and the New York morning. Push later than 5 PM GMT (12 PM EST) and the London team is checking out for the day. Push earlier than 1 PM GMT (8 AM EST) and the New York team is still on the subway. Major finance, law, media, and consulting firms run this corridor every working day, and the muscle memory is well-developed: book the call for 2 PM London (9 AM New York) and you cannot get it wrong.

Working-hour overlap

Strong overlap from 1 PM to 5 PM GMT (8 AM to 12 PM EST in winter, 9 AM to 1 PM EDT in summer), with 2 PM London the safest default.

When to schedule

Default to 2 PM London (9 AM New York in winter, 10 AM New York in summer-on-different-DST). Both sides are warm, neither side is rushed, and the slot sits well clear of London's end-of-day. For market-open coordination, 8:30 AM Eastern is 1:30 PM GMT, which is fine for London desks. For end-of-day reviews where London needs to drive, 4 PM GMT (11 AM EST) gives the New York team a full afternoon to react to anything London surfaces. Avoid scheduling on the two DST transition weeks (mid-March and late October) when the UK and US shift on different dates and the gap is briefly four hours.

Notable context

London is the largest financial center in Europe, and the London Stock Exchange opens at 8 AM GMT, which is 3 AM EST. New York's NYSE opens at 9:30 AM EST, which is 2:30 PM GMT. The narrow overlap between the two market opens (the four hours from 9:30 AM EST to 4:30 PM GMT) is when most US-UK equity research, sales-trading, and M&A coordination happens. Outside finance, the BBC, the FT, the Economist, and major UK media run on a more standard 9-to-6 GMT schedule, so an 11 AM New York call is just landing into a 4 PM London editorial close, workable but not relaxed.