Daylight saving time
London (United Kingdom) observes daylight saving time from the last Sunday of March to the last Sunday of October: UTC+0 in January, UTC+1 in July. New York (USA) observes daylight saving time from the second Sunday of March to the first Sunday of November: UTC−5 in January, UTC−4 in July. The two places switch on different dates, so for a few weeks in spring and autumn the difference is one hour different from the usual winter or summer value — the live clock above always shows the actual gap.
London uses GMT (UTC+0) in winter and British Summer Time (BST, UTC+1) in summer. New York is on US Eastern Time: EST (UTC−5) in winter and EDT (UTC−4) in summer.
Best time for a call
If both sides work 9:00–18:00 local time, the shared window is 14:00–18:00 in London = 09:00–13:00 in New York (4 hours). Put recurring calls in this window and state the time with the city name (for example “14:00 London time”) to avoid confusion. How to schedule a meeting across time zones.
How to read the chart
The left column is the local time in London, the other column shows the same moment in New York. “+1 day” means it is already the next calendar day in New York, “−1 day” — still the previous one. Rows outside 9:00–18:00 are dimmed. The converter above works the other way too: press “Swap” to enter a time in New York.