Convert GMT to EST
To convert GMT to EST: 12:00 PM GMT is 7:00 AM EST. GMT is UTC+00:00 and EST is UTC-05:00, so EST is 5 hours behind GMT, but not all year, as explained below.
In Eastern Standard Time
- On a 24-hour clock
- 12:00 GMT is 07:00 EST
- The offsets
- GMT is UTC+00:00, EST is UTC-05:00
- Difference
- EST is 5 hours behind GMT
- Date
- Same calendar day.
- This gap does NOT hold all year Convert through the offset in force on the date you care about.
- The two ends switch on different dates, or one does not switch at all.
- GMT is only in force part of the year European Union and United Kingdom: daylight time starts the last Sunday in March, at 01:00 UTC and ends the last Sunday in October, at 01:00 UTC (Directive 2000/84/EC). In 2026 that is 2026-03-29 to 2026-10-25. London and Dublin in winter is on BST between those dates.
- otherwise BST, UTC+01:00
- Military time zone letters Z (Zulu) is UTC. A to M run east of Greenwich an hour apart, N to Y west, and J is left out. A letter names an offset, so a zone that switches to daylight time changes letter: EST is R, EDT is Q.
- GMT is Z (Zulu), EST is R (Romeo)
- In Zulu notation Four digits on a 24-hour clock, no colon, then Z for UTC.
- 1200Z
- In every zone
- HST 02:00 AKST 03:00 PST 04:00 AKDT 04:00 MST 05:00 PDT 05:00 CST 06:00 MDT 06:00 EST 07:00 CDT 07:00 EDT 08:00 UTC 12:00 GMT 12:00 BST 13:00 CET 13:00 CEST 14:00 EET 14:00 EEST 15:00 MSK 15:00 IST 17:30 SGT 20:00 HKT 20:00 JST 21:00 AEST 22:00 AEDT 23:00 NZST 00:00 NZDT 01:00
How the Time Zone Converter works
Greenwich Mean Time (GMT) is UTC+00:00 and Eastern Standard Time (EST) is UTC-05:00, so converting GMT to EST means subtracting 5 hours from the GMT time. EST is 5 hours behind GMT.
Worked through: 12:00 PM GMT is 7:00 AM EST.
The gap between these two is not the same all year, which is the thing to get right. the two zones switch on different dates (GMT under the European Union and United Kingdom rule and EST under the United States one), so the difference moves. Convert through the offset in force on the date you care about rather than through the abbreviation somebody typed; the offsets above are definitions and the abbreviation is a claim about the calendar.
Five hours back in winter, four in summer, and the direction that most often produces a previous-day answer: anything before 05:00 in London is still the night before in New York. Note also that London is only on GMT for about five months of the year, from late October to late March. For the rest of it the city is on BST and a reader who converted from 'GMT' when they meant 'London' is an hour out.
One thing worth stating plainly, because it is the most common mistake in this whole subject: an abbreviation is not a place. GMT is Greenwich Mean Time, which London and Dublin in winter uses only part of the year; the rest of the time it is on BST at UTC+01:00. EST is likewise only in force for part of the year in New York; otherwise it is EDT at UTC-04:00. If what you have is a city and a date rather than a pair of abbreviations, that is a different question and needs the tz database, not arithmetic. This is also why the shifting designations exist: ET means Eastern time whichever of the two is in force. Searching for ET and searching for GMT to EST are the same question in two vocabularies, which is why this converter answers both.
Common times for this pair:
- 9:00 AM GMT is 4:00 AM EST - 12:00 PM GMT is 7:00 AM EST - 2:00 PM GMT is 9:00 AM EST - 5:00 PM GMT is 12:00 PM EST
Time Zone Converter FAQ
What is the time difference between GMT and EST?
EST is 5 hours behind GMT. GMT is UTC+00:00 and EST is UTC-05:00, and both offsets are definitions rather than measurements, so the subtraction is exact.
What time is 12:00 PM GMT in EST?
12:00 PM GMT is 7:00 AM EST. Subtract 5 hours and carry the date if it crosses midnight.
Does the difference between GMT and EST change with daylight saving?
Yes, and this is the main thing to watch on this pair. the two switch under different rules and on different dates, so the difference takes more than one value across the year. In 2026 the European Union and United Kingdom switch runs from 2026-03-29 to 2026-10-25.
Is there anything specific to this pair worth knowing?
Five hours back in winter, four in summer, and the direction that most often produces a previous-day answer: anything before 05:00 in London is still the night before in New York. Note also that London is only on GMT for about five months of the year, from late October to late March. For the rest of it the city is on BST and a reader who converted from 'GMT' when they meant 'London' is an hour out.
Someone wrote GMT but it is summer. What do they mean?
Almost certainly the zone rather than the abbreviation: London and Dublin in winter time, which in summer is BST at UTC+01:00 rather than GMT at UTC+00:00. People type the standard-time abbreviation all year round. If an invitation is an hour out from what you calculated, this is why.