The Quick Answer

The UK runs on Greenwich Mean Time (GMT) in winter and British Summer Time (BST) in summer. Both the UK and the United States use daylight saving time, so for most of the year the gap is steady: London is 5 hours ahead of New York and 8 hours ahead of Los Angeles.

The catch is that the two countries change their clocks on different dates. For a few weeks each spring and one week each autumn, the gap is one hour smaller: 4 hours from New York and 7 hours from Los Angeles. Those weeks are listed further down.

As of October 12, 2026, the hours when people on both sides are realistically awake (8 AM to 10 PM local time) are:

  • From the East Coast: 8 AM – 5 PM Eastern = 1 PM – 10 PM in London
  • From the West Coast: 8 AM – 2 PM Pacific = 4 PM – 10 PM in London

To check your own pair of cities for today’s date, open the time zone planner with New York and London already selected.

US Time Zone Cheat Sheet

England, Scotland, Wales, and Northern Ireland all share one time zone, so London, Edinburgh, Cardiff, and Belfast are always on the same clock. Reading tip: “5 hours ahead” means that when it is 9 AM where you are, it is 2 PM in London the same day.

For most of the year:

  • Eastern (EDT, UTC-4): London is 5 hours ahead. 9 AM New York = 2 PM London
  • Central (CDT, UTC-5): London is 6 hours ahead. 9 AM Chicago = 3 PM London
  • Mountain (MDT, UTC-6): London is 7 hours ahead. 9 AM Denver = 4 PM London
  • Pacific (PDT, UTC-7): London is 8 hours ahead. 9 AM Los Angeles = 5 PM London

During the changeover weeks (dates below):

  • Eastern (EDT, UTC-4): London is 4 hours ahead. 9 AM New York = 1 PM London
  • Central (CDT, UTC-5): London is 5 hours ahead. 9 AM Chicago = 2 PM London
  • Mountain (MDT, UTC-6): London is 6 hours ahead. 9 AM Denver = 3 PM London
  • Pacific (PDT, UTC-7): London is 7 hours ahead. 9 AM Los Angeles = 4 PM London

Most of Arizona and all of Hawaii do not change their clocks, so their gap with the UK follows its own pattern. The planner handles both.

When the Gap Changes: Exact Dates

These are the periods for New York and London through late 2027. Los Angeles is always three hours more.

  • October 12 – October 24, 2026: London is 5 hours ahead of New York
  • October 25 – October 31, 2026: London is 4 hours ahead of New York
  • November 1, 2026 – March 13, 2027: London is 5 hours ahead of New York
  • March 14 – March 27, 2027: London is 4 hours ahead of New York
  • March 28 – October 30, 2027: London is 5 hours ahead of New York
  • October 31 – November 6, 2027: London is 4 hours ahead of New York
  • November 7 – December 5, 2027: London is 5 hours ahead of New York

Why this happens: the US changes its clocks on the second Sunday of March and the first Sunday of November, while the UK changes on the last Sunday of March and the last Sunday of October. The UK dates in this period are October 25, 2026, March 28, 2027, October 31, 2027.

Family Calls vs. Work Calls

Work calls: use the shared office hours. A British workday is roughly 9 AM to 5 PM. The overlap with a 9-to-5 day in the US is narrow:

  • 9 AM – noon Eastern = 2 PM – 5 PM in London

From the West Coast there is no overlap of standard office hours at all, so a Pacific-time caller needs to start early: 8 AM Pacific is 4 PM in London.

Family calls: aim for their evening. People are home and relaxed between about 6 and 10 PM. That evening window in London corresponds to 1 PM – 5 PM Eastern = 6 PM – 10 PM in London; from the West Coast, 10 AM – 2 PM Pacific = 6 PM – 10 PM in London. The typical lunch break there is noon to 2 PM, which is a poor time to call.

What to Know Before You Call the UK

  • Keep work calls inside working hours. A typical office day is 9 AM to 5:30 PM, and many people protect their evenings. For a first business call, propose a time rather than ringing unannounced, and avoid Friday after about 4 PM.
  • Check for bank holidays. The UK has public holidays the US does not: the first and last Mondays of May, the last Monday of August in England and Wales, and Boxing Day on December 26. Offices are closed and people are often away.
  • Evenings are fine for family, within reason. For personal calls, 6 to 9 PM UK time is a comfortable window. Calling after 9:30 PM without warning is generally considered late.
  • Say the time with the city. Because both countries change their clocks on different dates, always write a proposed time with both cities, for example “3 PM London / 10 AM New York”, so there is no doubt during the changeover weeks.

Turn the Time Into an Invitation

Working out the hour is half the job; the other half is making sure the person on the other end reads the same time you meant. In the time zone planner, pick your city and London, choose a date and time under “Plan a call”, and copy the link. When they open it, the page shows the call in their local time and offers a calendar file. The calculation uses the clock rules for the exact date you picked, so it stays right across the daylight saving changeovers.

These figures were calculated on October 12, 2026 from the IANA time zone database (Europe/London and the four main US zones). Governments occasionally change their clock rules, so for a date far in the future, check again closer to the time.

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