EST explained
UTC−5, the 75°W meridian, the law behind it and the places that never leave it.
Basics · Eastern Time
EST vs EDT
EST (Eastern Standard Time) is UTC−5 and EDT (Eastern Daylight Time) is UTC−4. They are the winter and summer settings of one zone, Eastern Time (ET), and clocks move between them twice a year.
- Now in effect
- EST or EDT
- Current offset
- −05:00 / −04:00
- Next change
- Second Sunday in March
- Countdown
- —
What is the difference between EST and EDT?
Eastern Time is UTC−5 in winter (EST) and UTC−4 in summer (EDT).
| Feature | EST | EDT |
|---|---|---|
| Full name | Eastern Standard Time | Eastern Daylight Time |
| UTC offset | UTC−5 | UTC−4 |
| ISO 8601 suffix | -05:00 | -04:00 |
| In effect | 1st Sunday in November → 2nd Sunday in March | 2nd Sunday in March → 1st Sunday in November |
| Length | 18 or 19 weeks | Exactly 34 weeks |
| 9:00 AM Eastern in UTC | 14:00 UTC | 13:00 UTC |
| New York sunsets | about 4:30–6:00 PM | about 5:50–8:30 PM |
| Military letter | R (Romeo) | Q (Quebec) |
| Same offset as | Central Daylight Time; Panama and Jamaica all year | Atlantic Standard Time; Puerto Rico all year, Halifax in winter |
The difference is exactly one hour, and it is always the same hour: EDT is EST moved forward by 60 minutes. At any given instant a clock on EDT reads one hour later than a clock on EST, so 12:00 PM EST and 1:00 PM EDT are the same moment, 17:00 UTC.
Neither one is the "real" Eastern Time. US law defines the zone by its standard time, EST, and then advances clocks by an hour for daylight saving time; in practice the advanced setting is the one people live with for most of the year. The guide to EST covers its legal definition and the 75°W meridian behind UTC−5, and the guide to EDT covers what the extra evening hour does to sunrise and sunset. For the exact time right now, use the live Eastern Time clock.
How many weeks a year are EST and EDT in effect?
EDT always lasts exactly 34 weeks. The second Sunday in March falls between March 8 and 14, and the first Sunday in November between November 1 and 7, so the two Sundays are always 238 days apart; in 2027 they are March 14 and November 7. Because the March changeover day has only 23 hours, the season is 5,711 hours of real time.
EST gets the remainder: 127 days of a calendar year (128 in a leap year), about 35%. Counted from one changeover to the next, a winter on EST lasts 18 weeks (126 days) in most years and 19 weeks (133 days) in some, such as November 1, 2026 to March 14, 2027.
The split used to be closer. From 1987 to 2006, EDT ran from the first Sunday in April to the last Sunday in October, 29 or 30 weeks. The Energy Policy Act of 2005 moved the start three weeks earlier and the end one week later from 2007, adding four weeks (five in some years), and turned standard time into the minority of the year. The history of Eastern Time traces the earlier rules, and the daylight saving time guide lists every changeover date.
Should you write EST, EDT or ET?
Use the abbreviation that is actually in force on the date you mean, or use ET. An invitation for Friday, July 9, 2027 that says 3:00 PM EST
literally names 4:00 PM EDT, because 3:00 PM EST is 20:00 UTC. Most readers silently correct the slip, but a deadline written in EST for a June date leaves room for argument, and software does not correct anything: the EST page shows how a system set to "EST" ends up an hour off all summer.
| Situation | Write | Example |
|---|---|---|
| One event between early November and mid-March | EST | Tuesday, January 12, 2027, 10:00 AM EST |
| One event between mid-March and early November | EDT | Friday, July 9, 2027, 3:00 PM EDT |
| Recurring or undated times | ET | Weekdays, 9:00 AM–5:00 PM ET |
| A date near a changeover, or you're unsure | ET plus UTC | Monday, March 15, 2027, 9:00 AM ET (13:00 UTC) |
| Calendars, databases, code | IANA zone | America/New_York |
| Aviation, military, server logs | UTC | 13:00Z |
ET is never wrong, because it means "whatever Eastern clocks show on that date". Style guides differ on capitalisation and on when the short forms are acceptable; the Eastern Time abbreviations guide covers AP style, the French labels HNE and HAE and the military letters, while the UTC offset guide explains why software should store America/New_York rather than a fixed −05:00.
How does the switch between EST and EDT work?
- EST → EDT: on the second Sunday in March, clocks go from 1:59:59 AM EST straight to 3:00:00 AM EDT. The instant is 07:00 UTC, and the day has 23 hours.
- EDT → EST: on the first Sunday in November, clocks go from 1:59:59 AM EDT back to 1:00:00 AM EST at 06:00 UTC. The hour from 1:00 to 1:59 AM happens twice, and the day has 25 hours.
Because the rule is tied to 2:00 AM local time, the whole Eastern zone, from Maine to the Florida Keys and from Quebec to Georgia, switches at one instant; Central Time follows an hour later. In your own time zone, the spring 2027 change on March 14 happens at 07:00 UTC. A minute-by-minute look at spring-forward night is on the EDT page.
Where can you learn the rest of the Eastern Time basics?
Each basics page answers one question in depth, so this comparison does not have to:
- What EST is: the federal definition, the 75°W meridian and the places that stay on UTC−5 all year.
- What EDT is: the 2027 season, why it matches Atlantic time and how it moves sunrise and sunset.
- The UTC offset of Eastern Time: −05:00 and −04:00 in ISO 8601, conversion to UTC and sign traps in software.
- ET, EST, EDT and older labels: Eastern War Time, Eastern Prevailing Time, HNE/HAE and clashing codes such as CST and IST.
- The history of Eastern Time: from railway time in 1883 to the 2007 extension of daylight saving.
- Time zone boundaries: why the Eastern–Central line zigzags through five states.
- Military and 24-hour time: reading times such as 1400R or 13:00Z.
- The glossary: UTC, GMT, local mean time, IANA and other terms in one place.
Frequently asked questions
Is EDT one hour ahead of EST?
Yes. At any instant a clock on EDT shows one hour later than a clock on EST. You can only see both side by side across a border: in July, Kingston, Jamaica, which stays on EST all year, is one hour behind New York on EDT.
Does any US state stay on EST all year?
Not today. Federal law lets a state opt out of daylight saving time and keep standard time all year, as Arizona and Hawaii do, but every state in the Eastern zone observes EDT. Indiana was the long-running exception: Indianapolis and most of the state stayed on EST all year from 1971 until 2006.
Will EST or EDT become permanent?
Not yet. The Sunshine Protection Act (H.R. 139), which would make daylight time permanent nationwide (EDT all year in the East) while letting states opt out, passed the House on July 14, 2026 by 308 votes to 117. As of November 2026 the Senate has not voted on it; it sits with the Senate Commerce Committee, so clock changes continue and the March 14, 2027 change is still law.
Do Ontario and Quebec use EST and EDT too?
Yes. The Eastern parts of Ontario and Quebec switch on the same dates as the United States, so Toronto, Ottawa and Montreal always match New York. In French the labels are HNE and HAE. Ontario passed a law in 2020 for permanent daylight time, but it only takes effect if Quebec and New York State do the same, and it has not been brought into force.
Why is it called daylight time?
Moving clocks forward shifts an hour of daylight from the early morning, when most people are asleep, to the evening. The sun keeps exactly the same schedule; only the numbers on the clock change.
Explore
EDT explained
UTC−4 from March to November, its link to Atlantic time and its later sunsets.
DST 2027
Exact changeover instants for 2027, including the weeks when Europe is out of step.
Time zone converter
Convert any Eastern time to another zone, with daylight saving handled on both sides.