EST vs EDT
When each offset is in force, how long each lasts and which label to write.
Basics · UTC offset
Eastern Time UTC offset
Eastern Time is UTC−5 (written −05:00) from early November to mid-March and UTC−4 (−04:00) from mid-March to early November. To get UTC, add five hours to an EST time or four hours to an EDT time.
- ET offset now
- −05:00 / −04:00
- Eastern Time now
- --:-- ET
- UTC now
- --:-- UTC
- Next offset change
- Second Sunday in March
How is the Eastern Time offset written?
| Notation | EST | EDT | Where you see it |
|---|---|---|---|
| Everyday | UTC−5 | UTC−4 | Signs, articles, "GMT−5" on older sites |
| ISO 8601 extended | -05:00 | -04:00 | RFC 3339, JSON APIs, HTML datetime |
| ISO 8601 basic | -0500 | -0400 | Email Date: headers, compact logs |
| Minutes from UTC | −300 | −240 | Date libraries, the helpers on this site |
| Military letter | R | Q | Military messages |
A timestamp carries the local clock reading plus the offset, so both of these are 9:00 AM in New York: 2027-01-15T09:00:00-05:00 in winter and 2027-07-15T09:00:00-04:00 in summer. In UTC they are 2027-01-15T14:00:00Z and 2027-07-15T13:00:00Z. RFC 3339, the internet profile of ISO 8601, requires the colon form or Z, and it reserves -00:00 to mean "UTC is known but the local offset is not".
In machine formats the minus is the ASCII hyphen-minus; the typographic minus (−) used on this site is for prose only and will break a parser. The newer RFC 9557 (April 2024) lets a timestamp carry the zone name as well, 2027-07-15T09:00:00-04:00[America/New_York], which preserves both the instant and the rules that produced it. The letters R and Q are explained in the military time guide.
How do you convert Eastern Time to UTC?
- Check the date. From the second Sunday in March to the first Sunday in November the zone is on EDT; otherwise it is on EST.
- Add five hours for EST or four for EDT. To go from UTC back to Eastern, subtract instead.
- If the result passes midnight, move the date: 9:30 PM EST on January 15 is 02:30 UTC on January 16.
| Eastern Time | Offset | UTC |
|---|---|---|
| Friday, January 15, 2027, 9:00 AM | −05:00 | 14:00, January 15 |
| Friday, January 15, 2027, 9:30 PM | −05:00 | 02:30, January 16 (next day) |
| Thursday, July 15, 2027, 9:00 AM | −04:00 | 13:00, July 15 |
| Thursday, July 15, 2027, 10:00 PM | −04:00 | 02:00, July 16 (next day) |
| Sunday, March 14, 2027, 1:30 AM | −05:00 | 06:30, March 14 |
| Sunday, March 14, 2027, 2:30 AM | none | Does not exist: clocks skip to 3:00 AM |
| Sunday, November 7, 2027, 1:30 AM | −04:00 or −05:00 | 05:30 or 06:30: happens twice |
For a full 24-hour list in both seasons, see EST to UTC.
Why do EST5EDT and Etc/GMT+5 use a plus sign?
Not every system counts in the same direction. ISO 8601, RFC 3339 and everyday usage treat zones west of Greenwich as negative, so Eastern Time is −05:00. POSIX, the Unix standard behind the TZ variable, does the opposite: its number is what you add to local time to reach UTC. The classic setting EST5EDT,M3.2.0,M11.1.0 therefore reads "EST, five hours behind UTC; EDT; change on the second Sunday of March and the first Sunday of November".
The tz database's fixed-offset zones inherit that convention, so Etc/GMT+5 is five hours behind UTC, the same as EST without daylight saving, and Etc/GMT-5 is five hours ahead, the offset of Pakistan. JavaScript's getTimezoneOffset() also counts westward, in minutes: it returns 300 in EST and 240 in EDT.
Legacy names hide a second trap. EST5EDT applies US federal rules but pretends standard time existed forever, so it is wrong for older New York dates, and its maintainers recommend America/New_York for new software.
Why should software store UTC and use America/New_York?
An offset describes one instant; a zone describes the rules. −05:00 is right for a January timestamp and wrong for a July one, so no fixed offset can represent "Eastern Time". The robust pattern has three parts:
- Store past events, such as logs, payments and sensor readings, as UTC instants.
- Convert to local time only for display, using an IANA zone such as
America/New_York. - Store future local events, such as a 9:00 AM meeting next July, as the wall-clock time plus the zone ID, and work out the UTC instant when it is needed.
The third rule exists because offsets change by law. On September 17, 2026, Manitoba announced it would stop changing clocks and keep UTC−5 from November 1; the tz database shipped the change in release 2026e on September 29, and devices with older data show Winnipeg an hour off this winter. A system that stored −06:00 for future Winnipeg dates would need manual repairs; one that stored America/Winnipeg needs only the data update. The same would apply in the East if Congress ever made daylight time permanent.
Within the Eastern zone several IDs exist, including America/New_York, America/Toronto, America/Detroit and America/Indiana/Indianapolis; their rules are identical today but their histories differ, so pick the one for the place. Abbreviations are worse than offsets, because EST, CST and IST each mean more than one thing; the abbreviations guide lists the collisions and the glossary defines the terms.
How does Eastern Time compare with other UTC offsets?
| Place | Offset (Jan) | Offset (Jul) | At 12:00 PM ET (Jan) | At 12:00 PM ET (Jul) |
|---|---|---|---|---|
| New York (ET) | −05:00 | −04:00 | 12:00 PM | 12:00 PM |
| Los Angeles | −08:00 | −07:00 | 9:00 AM | 9:00 AM |
| Denver | −07:00 | −06:00 | 10:00 AM | 10:00 AM |
| Phoenix | −07:00 | −07:00 | 10:00 AM | 9:00 AM |
| Chicago | −06:00 | −05:00 | 11:00 AM | 11:00 AM |
| San Juan, Puerto Rico | −04:00 | −04:00 | 1:00 PM | 12:00 PM |
| Halifax | −04:00 | −03:00 | 1:00 PM | 1:00 PM |
| São Paulo | −03:00 | −03:00 | 2:00 PM | 1:00 PM |
| UTC | +00:00 | +00:00 | 5:00 PM | 4:00 PM |
| London | +00:00 | +01:00 | 5:00 PM | 5:00 PM |
| Paris, Berlin | +01:00 | +02:00 | 6:00 PM | 6:00 PM |
| Dubai | +04:00 | +04:00 | 9:00 PM | 8:00 PM |
| India | +05:30 | +05:30 | 10:30 PM | 9:30 PM |
| Shanghai | +08:00 | +08:00 | 1:00 AM (next day) | 12:00 AM (next day) |
| Tokyo | +09:00 | +09:00 | 2:00 AM (next day) | 1:00 AM (next day) |
| Sydney | +11:00 | +10:00 | 4:00 AM (next day) | 2:00 AM (next day) |
The gap with Eastern Time is constant only for places that change clocks on the same North American dates. Where a zone keeps one offset all year, as in Phoenix, San Juan, Dubai or Tokyo, the gap shrinks by an hour while the East is on EDT. Europe switches on the last Sundays of March and October, so for two or three weeks in March and one week around the start of November London is four hours ahead instead of five. Sydney's seasons run the other way, which turns a 16-hour gap in January into 14 hours in July. To see the current offsets for any time, use the live Eastern Time clock and converter.
Frequently asked questions
Is Eastern Time GMT−5 or GMT−4?
Both, at different times of year: GMT−5 (UTC−5) during EST and GMT−4 (UTC−4) during EDT. For everyday purposes a GMT offset and a UTC offset mean the same thing.
Why are some offsets not whole hours?
A few places chose half- or quarter-hour offsets: India is UTC+05:30, Nepal UTC+05:45 and Newfoundland UTC−03:30 in winter. That is why India is 10½ hours ahead of EST but only 9½ hours ahead of EDT.
What does the Z at the end of a timestamp mean?
Z marks UTC itself, an offset of +00:00. It comes from the military letter for the zero meridian, read Zulu. 2027-01-15T14:00:00Z is 9:00 AM EST on the same day.
Does Toronto have the same UTC offset as New York?
Yes, on every current date: both use −05:00 in winter and −04:00 in summer and change at the same instant. Their IANA zone IDs differ only because their clock histories before the 1970s differ.
Explore
EST to UTC
An hour-by-hour Eastern-to-UTC table for both seasons, plus the converter.
Everywhere at UTC−5
The countries and territories that share EST's offset, and which of them change clocks.
Military time
24-hour notation and the zone letters, from Z for UTC to R and Q for Eastern Time.