US Time Zone Abbreviations Table
| Zone | Standard | UTC std | Daylight | UTC dlt |
|---|---|---|---|---|
| Eastern | EST | -5 | EDT | -4 |
| Central | CST | -6 | CDT | -5 |
| Mountain | MST | -7 | MDT | -6 |
| Pacific | PST | -8 | PDT | -7 |
| Alaska | AKST | -9 | AKDT | -8 |
| Hawaii | HST | -10 | no DST | -10 |
US time zones come in two forms - a name (Eastern), a two-hour abbreviation pair (EST for standard, EDT for daylight) - and a UTC offset that shifts by one between them. The table below lists all six zones Americans actually meet, from Eastern's UTC-5/UTC-4 to Hawaii's fixed UTC-10, with what each letter pair stands for and where the zone runs. Most of the country spends eight months a year on the D form: daylight saving runs from the second Sunday in March to the first Sunday in November.
Two zones refuse to flip: Arizona (most of it) and Hawaii stay on standard time all year, which is why their tables read UTC-7 and UTC-10 in both columns. The offsets matter most in code and calendars - a timestamp marked 14:00 UTC is 9am EST but 6am PST, and the abbreviation on an invitation ('4pm ET') is doing quiet double duty: it names the zone AND tells you which offset to apply that week.
How to use
- Find the abbreviation you met (CST) and read across: what it stands for, its UTC offset in standard time, and the daylight variant (CDT, UTC-4).
- For a UTC timestamp, add the standard offset in winter and the daylight offset in summer - the tool shows both so the date arithmetic works either season.
- Check the annual flip dates on the daylight-saving dates table linked below before scheduling anything that crosses the March or November boundary.
Frequently asked questions
What does EST mean in time?
Eastern Standard Time, UTC minus 5 hours - the winter clock for the US East Coast. Its summer twin is EDT, Eastern Daylight Time, UTC minus 4. When someone writes '2pm EST' in July they usually mean 2pm in New York (which is actually EDT that week), so the safe reading of any abbreviation is 'local wall time' - and the precise reading is the UTC offset in this table applied to the date in question.
What is the UTC offset for each US time zone?
In standard time: Eastern UTC-5, Central UTC-6, Mountain UTC-7, Pacific UTC-8, Alaska UTC-9, Hawaii UTC-10. Daylight saving moves Eastern through Pacific one hour closer to UTC (EDT UTC-4 through PDT UTC-7); Alaska joins the flip (AKDT UTC-8) and Hawaii does not. UTC itself never changes - the offsets are what your local clock adds or subtracts, which is why UTC is the only safe way to store a moment in time.
Why do Arizona and Hawaii not change clocks?
Hawaii sits so close to the equator that its day length barely varies, making the shift pure annoyance, and it stayed on standard time permanently after 1945. Arizona opted out in 1968 for the same heat-driven reason - more evening daylight means more air conditioning. The practical twist: the Navajo Nation inside Arizona does observe DST, so the state runs two clocks for part of the year.
Is ET the same as EST?
Not quite - ET is the zone, EST/EDT are the seasons. 'ET' deliberately says 'Eastern Time, whichever offset is in force', which is why broadcasters and calendars prefer it: it stays correct across the March and November flip dates without anyone re-checking. Writing EST in summer or EDT in winter is a small but real error that shifts a converted UTC time by an hour.