Convert EST to GMT: Eastern Time to Greenwich Mean Time
Converting US Eastern Time (EST) to Greenwich Mean Time (GMT) is one of the most common scheduling moves for anyone working between the Americas and Europe/Africa. Eastern Time shifts with US daylight saving, so the gap to GMT changes twice a year. Here's the clean version.
Time Zone Overview
Eastern Time (EST/EDT)
US Eastern Time is EST (UTC−5) in winter and EDT (UTC−4) during US daylight saving (second Sunday in March to first Sunday in November).
Greenwich Mean Time (GMT)
GMT is UTC+0 in winter. The UK switches to BST (UTC+1) in summer, so the London reference also moves.
Time Difference
US winter (EST) / UK winter (GMT): GMT is 5 hours ahead of EST.
US summer (EDT) / UK summer (BST): GMT (as BST) is 4 hours ahead of EDT.
Mixed periods (limbo weeks): the gap can be 4 or 5 hours depending on which side has switched.
Conversion Formula
GMT = EST + 5 hours (both winter) / EST + 4 hours (both summer)
Quick Reference Table (EST → GMT/BST)
| EST (winter) | GMT | EDT (summer) | BST (London summer) |
|---|---|---|---|
| 7:00 AM | 12:00 PM | 7:00 AM | 12:00 PM |
| 9:00 AM | 2:00 PM | 9:00 AM | 2:00 PM |
| 12:00 PM | 5:00 PM | 12:00 PM | 5:00 PM |
| 3:00 PM | 8:00 PM | 3:00 PM | 8:00 PM |
| 6:00 PM | 11:00 PM | 6:00 PM | 11:00 PM |
| 9:00 PM | 2:00 AM (next day) | 9:00 PM | 2:00 AM (next day) |
Common Use Cases
- Scheduling London–New York calls
- Converting US market open/close to GMT for European traders
- Coordinating with UK teams from the US East Coast
- Reading event times quoted in GMT from the US
Frequently Asked Questions
What is the time difference between EST and GMT?
GMT is 5 hours ahead of EST in winter, 4 hours ahead in summer (when the US is on EDT and UK on BST).
If it's 9 AM EST, what time is it in London?
2:00 PM GMT (winter) or 2:00 PM BST (summer — same clock time, different label).
Does the UK use GMT year-round?
No. The UK uses GMT in winter and BST (UTC+1) in summer.
How do I convert EDT to GMT?
Add 4 hours in summer. In winter (EST), add 5 hours.
Why does my calendar show BST not GMT?
Because the UK is on summer time. BST = GMT+1, so the offset to US Eastern shrinks by an hour.
Use our world clock and meeting planner for live conversion.