Convert GMT to EST: Greenwich Mean Time to Eastern Time
Converting Greenwich Mean Time to Eastern Standard Time is foundational — GMT is the reference point for all UTC offsets. Subtracting 5 hours (or 4 during US DST) gives you US Eastern Time.
Time Zone Overview
GMT (UTC+0)
Greenwich Mean Time is the baseline. London uses it in winter; the UK switches to BST (UTC+1) in summer.
EST/EDT
Eastern Standard Time is UTC-5 (winter), EDT is UTC-4 (summer, second Sunday March to first Sunday November).
Conversion Formula
EST = GMT − 5 hours (winter) / GMT − 4 hours (US summer)
Conversion Examples
Winter: 12:00 PM GMT → 7:00 AM EST
US summer: 12:00 PM GMT → 8:00 AM EDT
Quick Reference Table (GMT → EST)
| GMT | EST/EDT |
|---|---|
| 12:00 AM | 7:00 PM (prev day) |
| 3:00 AM | 10:00 PM (prev day) |
| 6:00 AM | 1:00 AM |
| 9:00 AM | 4:00 AM |
| 12:00 PM | 7:00 AM |
| 3:00 PM | 10:00 AM |
| 6:00 PM | 1:00 PM |
| 9:00 PM | 4:00 PM |
Common Use Cases
- Converting flight/event times published in GMT/UTC
- Scheduling with US teams from Europe
- Reading international market open times
Frequently Asked Questions
How many hours behind is EST from GMT?
5 hours (4 during US DST).
Is GMT the same as UTC?
For practical conversion they are effectively identical (no leap seconds in daily use).
If it's noon GMT, what time is it in New York?
7 AM EST (winter) or 8 AM EDT (summer).
Does London on BST change GMT conversion?
The GMT↔EST math is fixed; BST is a separate London-local offset.
How do I convert EST to GMT?
Add 5 (winter) or 4 (summer) hours.
See our world clock for live GMT and Eastern times.