London

00:00:00

Greenwich Mean Time (GMT)

London: The Global Meridian Baseline

🕒 Time Zone Facts

UTC Offset: UTC+0 (GMT, winter) / UTC+1 (BST, summer).

DST Starts: Last Sunday in March, clocks move forward 1 hour.

DST Ends: Last Sunday in October, clocks move back 1 hour.

🌍 Why London Time Matters

London (GMT) is the reference point the world's time zone system is built around — it's "zero" on the UTC scale, which is why it's the default city most other time zones are measured against.

💼 Business Hours Overlap

London ↔ New York: 4-5 hr difference. Overlap ~9am–12pm ET (2pm–5pm GMT).

London ↔ Dubai: 3-4 hr difference. Overlap ~9am–1pm GMT.

London ↔ Tokyo: 8-9 hr difference. Minimal overlap; early AM London / evening Tokyo.

❓ Common Questions

Is London on GMT or BST right now? Check the live clock above — BST runs late March to late October, GMT the rest of the year.

Why does the UK change its clocks? To make better use of daylight in summer evenings, a practice dating to WWI-era energy-saving measures.

Planning Across Time Zones

London sits at the center of the world's chronological map as the home of the Greenwich Meridian. Operating on GMT during winter and BST (UTC+1) in summer, London time is the universal reference for global shipping, aviation, and internet protocols. If you're scheduling meetings across time zones, London's working hours give you a workable overlap with both the Americas in the morning and the Middle East/Asia in the afternoon.

How London Became the World's Time Reference

Before the 1800s, London didn't even keep a single time for itself. Towns across Britain kept their own "local solar time," which could differ from London by several minutes depending on longitude. It wasn't until the railways connected the country that this became a real problem — a train timetable is useless if every station clock disagrees.

Railway Time to Greenwich Mean Time

In the 1840s, British railway companies adopted a single standardized time — "Railway Time" — based on the Royal Observatory in Greenwich. It spread so widely that by 1880, Greenwich Mean Time became the legal standard across Great Britain.

From GMT to the World's Prime Meridian

In 1884, an international conference chose Greenwich as the world's Prime Meridian — the zero-degree line all other time zones are measured against. That's why UTC offsets today are still expressed as "UTC+" or "UTC-" relative to London's line.

GMT vs. BST Today

London still shifts to British Summer Time (BST, UTC+1) each year to make better use of evening daylight — a practice that began during WWI as a fuel-saving measure and has stuck ever since.