The Offset Right Now
London sits 5 hours ahead of New York in winter and 4 hours ahead in summer. That single number shifts four times a year.
- Winter (GMT): London is 5 hours ahead. 12:00 in London means 07:00 in New York.
- Summer (BST): London is 4 hours ahead. 12:00 in London means 08:00 in New York.
Check the live clocks. If London shows "BST", subtract 4 hours for New York. If it shows "GMT", subtract 5.
Why the Gap Moves: GMT/BST vs EST/EDT
London cycles between Greenwich Mean Time (GMT, UTC+0) in winter and British Summer Time (BST, UTC+1) in summer. New York switches between Eastern Standard Time (EST, UTC-5) and Eastern Daylight Time (EDT, UTC-4).
Both cities on standard time? 5 hours apart. Both on daylight saving? 4 hours. The catch: the UK and North America do not change clocks on the same dates.
The DST Gap: When the Offset Is 4 Hours Instead of 5
The UK changes clocks on the last Sunday of March and the last Sunday of October. North America changes on the second Sunday of March and the first Sunday of November.
Two windows each year, one city already shifted and the other waiting:
| Period | What happens | Offset |
|---|---|---|
| Second Sunday in March → Last Sunday in March | New York moves to EDT; London stays on GMT | 4 hours (London ahead) |
| Last Sunday in October → First Sunday in November | London moves to GMT; New York stays on EDT | 5 hours (London ahead) |
For 2026: London goes forward on Sunday 29 March and back on Sunday 25 October. New York goes forward on Sunday 8 March and back on Sunday 1 November.
The Business Overlap Window: 13:00-17:00 London Time
The core transatlantic window runs 13:00-17:00 London time, which is 08:00-12:00 New York time. Finance, legal, and media teams rely on this slot for real-time conversation.
The City of London financial district starts early. Many traders and analysts reach their desks by 07:00 London time. That stretches the usable overlap to include 12:00-13:00 London (07:00-08:00 New York), but only for people willing to take an early call in London or a late one in New York.
When the gap is 5 hours (winter), the London lunch hour lines up with the New York morning. A common slot for informal catch-ups. When the gap is 4 hours (summer), the overlap tilts slightly later in London and earlier in New York.
Quick Reference: Offset by Season
| Season | London offset | New York offset | Gap |
|---|---|---|---|
| Winter (both standard) | GMT (UTC+0) | EST (UTC-5) | 5 hours |
| Summer (both DST) | BST (UTC+1) | EDT (UTC-4) | 4 hours |
| March DST gap | GMT (UTC+0) | EDT (UTC-4) | 4 hours |
| October DST gap | BST (UTC+1) | EST (UTC-5) | 5 hours |
Using the Converter
The interactive tool does three things:
- Shows the current time in both cities with the correct label (GMT/BST for London, EST/EDT for New York).
- Lets you pick a date. Useful for scheduling a meeting next month or checking the gap during the DST misalignment weeks.
- Gives you the instant conversion for any hour you type in.
Confirm whether a 14:00 London call lands at 09:00 or 10:00 in New York. In October 2026, London falls back on 25 October but New York stays on EDT until 1 November. A meeting at 14:00 London on 28 October will be 09:00 New York. A 5-hour gap, not the 4-hour gap you might expect.
What the Next Clock Change Means
London goes forward on Sunday 29 March 2026 at 01:00 local time. BST begins. London jumps from UTC+0 to UTC+1. New York will already be on EDT (UTC-4), so the gap stays at 4 hours. But the first working day after the change, Monday 30 March, will feel like you lost an hour of morning in London.
Standing weekly call at 15:00 London / 10:00 New York in March? Check the date. Before 29 March the gap is 5 hours (15:00 London = 10:00 New York). After 29 March the gap is 4 hours (15:00 London = 11:00 New York). Your New York colleague will be an hour late if nobody adjusts.