The short answer: The UK (London) is 5 hours ahead of US Eastern Time and 8 hours ahead of US Pacific Time for most of the year. The best shared window is US morning to UK afternoon: 9 AM–12 PM ET lines up with 2–5 PM in London, when both sides are at their desks. During the brief spring and autumn windows when the clocks are out of sync, subtract an hour (4h to ET, 7h to PT).
Of all the long-haul pairings, the United States and the United Kingdom is one of the kindest. The UK is always ahead, so your morning is their afternoon, and there is a genuine block of the working day where everyone is awake at once.
How far ahead is the UK?
The UK is on GMT in winter and BST in summer, and the US shifts its clocks too. For most of the year the offsets below hold steady. They only wobble for the few weeks each spring and autumn when one country has changed its clocks and the other has not.
| Your US zone | UK ahead of you (most of year) | During the mismatch windows |
|---|---|---|
| Eastern (ET) | 5 hours | 4 hours |
| Central (CT) | 6 hours | 5 hours |
| Mountain (MT) | 7 hours | 6 hours |
| Pacific (PT) | 8 hours | 7 hours |
Worked conversions
Using the steady offsets (UK 5 hours ahead of ET, 8 hours ahead of PT), here is what common US times become in London.
| Your time | If you're on ET | If you're on PT |
|---|---|---|
| 9:00 AM | 2:00 PM London | 5:00 PM London |
| 12:00 PM | 5:00 PM London | 8:00 PM London |
| 5:00 PM | 10:00 PM London | 1:00 AM London (next day) |
The takeaway: from the East Coast, schedule before lunch and you'll catch London mid-afternoon. From the West Coast the overlap is narrower — your early morning is London's late afternoon, so 8 AM PT (4 PM London) is about the last comfortable slot before the UK clocks off.
The best shared window
For a meeting that suits both sides, aim for US morning against UK afternoon. 9 AM–12 PM ET is 2–5 PM in London, squarely inside everyone's working day. West Coast teams should start as early as they can: 7–8 AM PT is 3–4 PM London, which still lands before the UK day ends.
For a deeper look at one specific pair, see our guide to the London to New York time difference, or the best windows in our guide to calling the UK from the USA.
Both countries observe daylight saving, but the US changes its clocks before the UK in spring and after the UK in autumn. For roughly three weeks each time, the usual gap shrinks by an hour, so a recurring meeting can drift. Double-check any call that falls in mid-March or late October/early November.
Stop checking this every time
If you work across the Atlantic regularly, doing this arithmetic by hand gets old fast, and the brief daylight-saving mismatch is exactly where mistakes creep in. Atlas keeps London and your own US city side by side in your Mac menu bar, shades the hours when both sides are awake, and writes any meeting to your calendar in both local times. One glance tells you whether now is a good time to call.
Frequently asked
How many hours ahead is the UK of the USA?
What is the best time for a USA-UK meeting?
Why does the USA-UK gap change by an hour twice a year?
Stop doing timezone math
Atlas finds the time everyone's awake and adds it to your calendar in one tap.
One-time purchase, yours forever.