How many hours is EST behind GMT?

EST (Eastern Standard Time) is 5 hours behind GMT. When it is 12:00 PM GMT in London, it is 7:00 AM EST in New York. During US daylight saving time (March to November), the Eastern US uses EDT (UTC-4), which is only 4 hours behind GMT. But if the UK is also on BST (British Summer Time, UTC+1), the gap widens back to 5 hours. The actual difference depends on the time of year.

What is 9 AM EST in GMT?

9:00 AM EST is 2:00 PM GMT. Add 5 hours to convert EST to GMT during standard time (November through March). During US daylight saving when both the US and UK have switched, the math stays similar but the labels change: 9 AM EDT = 2 PM BST.

Why does the EST to GMT difference change during the year?

Because the US and UK switch to daylight saving on different dates. The US springs forward on the second Sunday in March. The UK springs forward on the last Sunday in March. For those 2-3 weeks in between, the US has already shifted but the UK has not, so the gap is only 4 hours instead of 5. The same thing happens in reverse in autumn: the US falls back on the first Sunday in November, the UK falls back on the last Sunday in October.

Is GMT the same as UTC?

For everyday purposes, yes. GMT and UTC both represent the zero-offset reference time. The technical difference is that UTC is defined by atomic clocks and is the official global standard, while GMT is the historical name tied to the Royal Observatory in Greenwich. In practice, when someone says GMT they mean UTC+0.

What is BST and how does it affect the conversion?

BST (British Summer Time) is the UK's daylight saving time. It is UTC+1, which means London moves 1 hour ahead of GMT from late March through late October. During BST, the difference between Eastern US time and London time is the same 5 hours (EDT is UTC-4, BST is UTC+1, difference = 5). The tricky weeks are when only one country has switched.

When do business hours overlap between EST and GMT?

The overlap window is roughly 9:00 AM to 12:00 PM EST, which is 2:00 PM to 5:00 PM GMT. That gives you about 3 hours where both New York and London offices are open during normal business hours. After noon Eastern, London is past 5 PM. Before 9 AM Eastern, London has not started yet (it would be before 2 PM there, but the US side is too early).

What is EST to GMT+1 (Central European Time)?

EST to CET (Central European Time, GMT+1) is a 6-hour difference during standard time. 9 AM EST = 3 PM CET. Paris, Berlin, Madrid, Rome, and Amsterdam are all in CET. During daylight saving, CET becomes CEST (GMT+2), but EDT is UTC-4, so the gap remains 6 hours for most of the year.

EST to GMT — Time Difference, Conversion Chart, and the DST Trap Nobody Warns You About

Last updated: April 202610 min readCalculator Tools

EST is 5 hours behind GMT. Add 5 hours to any Eastern time to get Greenwich Mean Time. But there is a catch that burns people every March and October.

Unlike EST to PST (which stays a constant 3 hours apart all year), the EST-GMT gap actually shifts during daylight saving transitions. The US and UK change their clocks on different weekends, and for 2-3 weeks twice a year, the math changes. This guide covers the standard conversion, the DST trap, and when US-UK business hours actually overlap.

Convert between EST, GMT, and all world zones instantly. Handles DST automatically.

Open Timezone Converter

Standard Conversion: EST to GMT Hour-by-Hour

During standard time (early November through mid-March), the rule is simple: add 5 hours.

EST (New York)	GMT (London)	Notes
12:00 AM (midnight)	5:00 AM	Same calendar day
3:00 AM	8:00 AM
5:00 AM	10:00 AM
6:00 AM	11:00 AM
7:00 AM	12:00 PM	London lunch
8:00 AM	1:00 PM
9:00 AM	2:00 PM	US-UK overlap starts
10:00 AM	3:00 PM	Peak overlap
11:00 AM	4:00 PM	Peak overlap
12:00 PM (noon)	5:00 PM	London offices closing
1:00 PM	6:00 PM	London is done for the day
2:00 PM	7:00 PM
3:00 PM	8:00 PM
5:00 PM	10:00 PM
7:00 PM	12:00 AM (next day)	Date rolls forward in London
9:00 PM	2:00 AM (next day)
11:00 PM	4:00 AM (next day)

The blue rows show the business-hours overlap window. You get about 3 hours (9 AM - noon EST / 2 PM - 5 PM GMT) where both sides are comfortably at work.

The DST Trap: When the 5-Hour Rule Breaks

This is the part that catches people off guard. The US and UK do not switch to daylight saving on the same dates.

Event	US (Eastern)	UK
Spring forward	2nd Sunday in March	Last Sunday in March
Fall back	1st Sunday in November	Last Sunday in October

This mismatch creates two awkward windows every year where the difference is NOT 5 hours:

Spring gap (2-3 weeks in March)

The US springs forward in early March. The UK does not spring forward until late March. For those 2-3 weeks, the US has jumped ahead by 1 hour but the UK has not. Result: the gap narrows to 4 hours instead of 5.

So during mid-March: 9 AM EDT (not EST anymore) = 1 PM GMT. Not 2 PM. If you have a recurring 9 AM Eastern / 2 PM London meeting, it suddenly becomes 9 AM Eastern / 1 PM London for those weeks. Miss this and someone shows up an hour late.

Autumn gap (1 week in late October / early November)

The UK falls back on the last Sunday in October. The US does not fall back until the first Sunday in November. For that week, the UK has dropped back but the US has not. Result: the gap widens to 4 hours again (from a different direction).

The four seasons of EST-GMT conversion

Period	US Zone	UK Zone	Difference	Math
Nov - early Mar	EST (UTC-5)	GMT (UTC+0)	5 hours	Add 5
Early Mar - late Mar	EDT (UTC-4)	GMT (UTC+0)	4 hours	Add 4 (trap!)
Late Mar - late Oct	EDT (UTC-4)	BST (UTC+1)	5 hours	Add 5
Late Oct - early Nov	EDT (UTC-4)	GMT (UTC+0)	4 hours	Add 4 (trap!)

The orange rows are the trap weeks. Most of the year you are fine with "add 5." But twice a year, for 1-3 weeks, it is "add 4." If you schedule recurring US-UK meetings, put a calendar reminder on both DST switch dates and re-check your meeting times.

Or just use a timezone converter that reads your device's current DST status and handles it automatically. No mental math needed.

Most-Searched Specific Conversions

These are the exact EST-to-GMT conversions people search for most. All shown for standard time (add 5). During the March/October trap weeks, subtract 1 hour from the GMT column.

EST	GMT
8:00 AM EST	1:00 PM GMT
9:00 AM EST	2:00 PM GMT
10:00 AM EST	3:00 PM GMT
11:00 AM EST	4:00 PM GMT
12:00 PM EST	5:00 PM GMT
1:00 PM EST	6:00 PM GMT
2:00 PM EST	7:00 PM GMT
3:00 PM EST	8:00 PM GMT
5:00 PM EST	10:00 PM GMT
6:00 PM EST	11:00 PM GMT
8:00 PM EST	1:00 AM GMT (next day)
12:00 AM EST (midnight)	5:00 AM GMT

US-UK Business Hour Overlap

This is the practical question for anyone working with London colleagues, clients, or vendors.

Window	EST (New York)	GMT (London)	Verdict
Sweet spot	10:00 - 11:00 AM	3:00 - 4:00 PM	Both sides alert and available
Good	9:00 AM - 12:00 PM	2:00 - 5:00 PM	Full 3-hour window
Stretching it	7:00 - 9:00 AM	12:00 - 2:00 PM	US side needs to be early
Avoid	After 12:00 PM	After 5:00 PM	London is off the clock

The honest window is about 3 hours. If you regularly work with UK teams, 10 AM EST / 3 PM GMT is the single best meeting time. Both sides are in the middle of their workday. We covered multi-zone scheduling strategies in detail in our cross-timezone meeting guide.

Real Scenarios

The earnings call

A company announces earnings at "4:05 PM ET after market close." You are in London. That is 9:05 PM GMT in winter, or 9:05 PM BST in summer. Either way, it is late evening. If you follow US markets from the UK, earnings season means late nights.

The transatlantic job interview

Your interviewer in London says "Can we do 3 PM our time?" That is 10 AM EST. Confirm it in writing: "3 PM GMT / 10 AM EST on Thursday." And double-check if you are in one of the DST trap weeks. A calendar invite with timezone set correctly solves this automatically.

Premier League kickoffs for US viewers

A 3 PM GMT Saturday kickoff in the English Premier League is 10 AM EST. An early 12:30 PM GMT match is 7:30 AM EST. And those midweek 8 PM GMT matches? 3 PM EST, which actually works out well for the East Coast.

Deadline with a UK client

"We need the deliverable by end of day Friday GMT." End of day in London is 5:00 PM GMT = 12:00 PM EST. You have until noon Eastern. Not end of day Eastern. This catches people who assume "end of day" means their end of day.

GMT vs UTC vs BST — Clearing Up the Confusion

These get mixed up constantly. Here is the short version:

GMT (Greenwich Mean Time) — UTC+0. The baseline. Used in the UK from late October to late March.
UTC (Coordinated Universal Time) — Effectively the same as GMT for daily use. The official global standard. Never changes for daylight saving.
BST (British Summer Time) — UTC+1. Used in the UK from late March to late October. London is 1 hour ahead of GMT during BST.

When someone says "GMT" in summer, they usually mean "UK time" (which is actually BST, UTC+1). Technically wrong, but universally understood. If precision matters (server timestamps, flight times, contracts), use UTC and a specific offset number.

Our timestamp converter works with UTC offsets directly if you need epoch-level precision.

EST to Other European Zones

GMT is just the starting point. If your contacts are in mainland Europe, the math changes:

From EST →	Zone	Difference	Example (9 AM EST)	Cities
GMT	UTC+0	+5 hours	2:00 PM	London, Dublin, Lisbon
CET	UTC+1	+6 hours	3:00 PM	Paris, Berlin, Madrid, Rome, Amsterdam
EET	UTC+2	+7 hours	4:00 PM	Athens, Helsinki, Bucharest, Kyiv
MSK	UTC+3	+8 hours	5:00 PM	Moscow, Istanbul, Riyadh

Notice how the overlap shrinks fast. US East Coast and London get 3 comfortable hours. US East Coast and Athens get maybe 2. US East Coast and Moscow? Almost nothing during standard business hours.

EST to GMT in 24-Hour / Military Time

EST (24h)	GMT (24h)	Standard
0000	0500	12 AM / 5 AM
0600	1100	6 AM / 11 AM
0900	1400	9 AM / 2 PM
1200	1700	12 PM / 5 PM
1500	2000	3 PM / 8 PM
1800	2300	6 PM / 11 PM
2100	0200 (+1)	9 PM / 2 AM next day

Quick Conversion Tool

If you deal with EST-GMT conversions regularly, stop doing the mental math. Our timezone converter reads your device clock, automatically detects whether DST is active in both zones, and gives you the correct answer in under a second. It also shows a world clock with 10 cities at a glance.

For a broader comparison of timezone tools, including what Reddit users recommend, check our Reddit timezone converter roundup. And for a full reference covering all world zones (not just EST and GMT), see our complete timezone guide.

Convert EST to GMT (and any other zone) instantly. DST handled automatically.