US Time Zones Explained: EST, CST, MST, PST and How They Work
The US has nine legal time zones, but only six of them cover the 50 states. Most people only deal with four: Eastern, Central, Mountain and Pacific. The abbreviations are what trip people up. Is it EST or EDT? CST or CDT? The answer depends on the month, and the same city uses both in one year.
This page covers what each zone includes, where the borders cut through states, how daylight saving time moves them, and the gaps between them, including the Arizona exception that catches out most schedules.
How Many Time Zones Does the US Have?
US law names nine standard time zones: Atlantic, Eastern, Central, Mountain, Pacific, Alaska, Hawaii-Aleutian, Samoa and Chamorro (49 CFR Part 71, the federal rule that sets them). Six of them cover the states: the four contiguous zones plus Alaska and Hawaii-Aleutian. Puerto Rico and the US Virgin Islands are on Atlantic time, American Samoa is on Samoa time and Guam and the Northern Mariana Islands are on Chamorro time.
For scheduling, the four contiguous zones matter most: Eastern, Central, Mountain and Pacific. Eastern is the busiest. It covers the East Coast corridor from Maine to Florida plus Ohio, Georgia and most of Michigan, which is why US markets, national broadcasts and many company calendars are written in Eastern Time.
The table shows each zone's offset from UTC and the dates the US switches in 2026 (second Sunday in March, first Sunday in November, at 2:00 AM local time).
| Zone | Winter (standard) | Summer (daylight) | 2026 summer period |
|---|---|---|---|
| Eastern | UTC-5 (EST) | UTC-4 (EDT) | March 8 to November 1 |
| Central | UTC-6 (CST) | UTC-5 (CDT) | March 8 to November 1 |
| Mountain | UTC-7 (MST) | UTC-6 (MDT) | March 8 to November 1 |
| Pacific | UTC-8 (PST) | UTC-7 (PDT) | March 8 to November 1 |
| Alaska | UTC-9 (AKST) | UTC-8 (AKDT) | March 8 to November 1 |
| Hawaii | UTC-10 (HST) | UTC-10 (no change) | none |
| Arizona (most) | UTC-7 (MST) | UTC-7 (no change) | none |
Eastern Time Zone (EST / EDT)
UTC offset: UTC-5 in winter (EST), UTC-4 in summer (EDT).
States covered: New York, Florida (most of it), Georgia, Pennsylvania, Ohio, Michigan (most of it), Virginia, North Carolina, South Carolina, Massachusetts, New Jersey, Maryland, Connecticut, Delaware, Rhode Island, Vermont, New Hampshire, Maine, and parts of Indiana, Kentucky and Tennessee.
Major cities: New York City, Miami, Boston, Philadelphia, Atlanta, Detroit, Washington D.C., Charlotte.
The New York Stock Exchange runs on this clock, with trading from 9:30 AM to 4:00 PM Eastern. In March the East Coast's offset goes from -5 to -4, and in November it goes back.
The Indiana split: Most of Indiana is Eastern, but twelve counties are Central: Lake, Porter, LaPorte, Newton, Jasper and Starke in the northwest, in Chicago's orbit, and Gibson, Perry, Posey, Spencer, Vanderburgh and Warrick in the southwest, around Evansville (Visit Indiana's list). Indiana only began observing daylight saving time statewide in 2006; before that, most counties stayed on standard time all year. The Indiana time zone page has the full county list.
Kentucky is split too. The boundary runs roughly through the middle of the state. Louisville and Lexington are Eastern, and Bowling Green and the west of the state are Central.
Central Time Zone (CST / CDT)
UTC offset: UTC-6 in winter (CST), UTC-5 in summer (CDT).
States covered: Illinois, Texas (most of it), Minnesota, Wisconsin, Iowa, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Oklahoma, Middle and West Tennessee, most of Kansas, Nebraska, North Dakota and South Dakota, western Kentucky, the western Florida Panhandle and four Michigan counties.
Major cities: Chicago, Dallas, Houston, San Antonio, Austin, Nashville, Minneapolis, St. Louis, New Orleans.
Central is always one hour behind Eastern. Chicago is 1 hour behind New York in January and still 1 hour behind in July, because both zones move on the same date.
The Tennessee split: East Tennessee, including Knoxville and Chattanooga, is Eastern. Nashville and Memphis are Central. The Tennessee page shows the line.
Texas: El Paso and Hudspeth counties, at the far western end, are Mountain. The Central and Mountain boundary is set in 49 CFR 71.7, which follows the east line of Hudspeth County. The rest of the state is Central; see the Texas page.
Other small pieces: four Upper Peninsula counties of Michigan (Gogebic, Iron, Dickinson and Menominee) are Central, and the Florida Panhandle west of the Apalachicola River is Central; see the Florida page.
Mountain Time Zone (MST / MDT)
UTC offset: UTC-7 in winter (MST), UTC-6 in summer (MDT).
States covered: Colorado, Utah, New Mexico, Wyoming, Montana, southern Idaho, most of Arizona (see below), and slices of Oregon (most of Malheur County), Nevada (West Wendover), Texas, Kansas, Nebraska, North Dakota and South Dakota.
Major cities: Denver, Salt Lake City, El Paso, Albuquerque, Boise, Billings.
The Arizona exception: Arizona does not observe daylight saving time. It has stayed on Mountain Standard Time (UTC-7) all year since 1968, with no spring forward and no fall back. That means Arizona's relation to its neighbours changes twice a year:
- In winter Arizona has the same time as Colorado and Utah (both MST, UTC-7).
- In summer Colorado and Utah move to MDT (UTC-6). Arizona stays at UTC-7, an hour behind them, and shows the same time as California (PDT, also UTC-7).
The Navajo Nation, which covers a large part of northeastern Arizona, does observe daylight saving time, while the Hopi Reservation inside it follows the rest of Arizona. The Arizona time zone page explains this and shows the boundary.
Hawaii is the only other state that skips daylight saving time. Puerto Rico and the other territories also keep one clock all year.
Pacific Time Zone (PST / PDT)
UTC offset: UTC-8 in winter (PST), UTC-7 in summer (PDT).
States covered: California, Washington, most of Oregon, most of Nevada, and northern Idaho (the Panhandle, north of the Salmon River).
Major cities: Los Angeles, San Francisco, Seattle, Portland, Las Vegas, San Diego, Sacramento.
Pacific is always three hours behind Eastern. 9 AM EST is 6 AM PST in winter, and 9 AM EDT is 6 AM PDT in summer. So a 9 AM Eastern call means a 6 AM start on the West Coast, and a 5 PM Pacific deadline is 8 PM in New York, past the working day there. Much of US finance and media is scheduled in Eastern time, while many technology companies are in California, so announcements are often given in Pacific time and need converting for everyone else.
Alaska and Hawaii: The Outliers
Alaska (AKST / AKDT): UTC-9 in winter, UTC-8 in summer. Anchorage, Juneau and Fairbanks all observe daylight saving time. The Aleutian Islands west of 169°30′ W use Hawaii-Aleutian time instead, which is UTC-10 in winter and UTC-9 in summer.
Hawaii (HST): UTC-10 all year, with no daylight saving time. Honolulu is 5 hours behind New York in winter and 6 hours behind in summer. It is 2 hours behind Los Angeles in winter and 3 in summer, because Los Angeles moves and Hawaii doesn't.
A Quick Reference for US-to-US Time Conversions
Because the zones change on the same date, these gaps hold all year:
| Pair | Gap |
|---|---|
| Eastern and Central | 1 hour (Eastern ahead) |
| Eastern and Mountain | 2 hours (Eastern ahead) |
| Eastern and Pacific | 3 hours (Eastern ahead) |
| Eastern and Alaska | 4 hours (Eastern ahead) |
| Central and Mountain | 1 hour (Central ahead) |
| Central and Pacific | 2 hours (Central ahead) |
| Mountain and Pacific | 1 hour (Mountain ahead) |
The exception is the few hours on the day of the change. Each zone switches at 2:00 AM local time, so Eastern moves an hour before Central does. On March 8, 2026, for one hour, between 07:00 and 08:00 UTC, New York was on EDT while Chicago was still on CST, and the gap was 2 hours instead of 1.
Arizona and Hawaii break the pattern, because they don't change:
| From | To | Winter | Summer |
|---|---|---|---|
| New York | Arizona | 2 hours | 3 hours |
| Chicago | Arizona | 1 hour | 2 hours |
| Los Angeles | Arizona | Arizona 1 hour ahead | same time |
| New York | Hawaii | 5 hours | 6 hours |
| Los Angeles | Hawaii | 2 hours | 3 hours |
The Abbreviations That Confuse Everyone
The S and D in each abbreviation stand for Standard and Daylight:
- EST is Eastern Standard Time (winter), EDT is Eastern Daylight Time (summer).
- CST / CDT are Central, MST / MDT are Mountain, PST / PDT are Pacific.
People write "EST" all year to mean "Eastern Time", although in July the East Coast is on EDT. In conversation that is usually understood. In software, contracts and filings it is not, because "EST" is exactly UTC-5, so a meeting "at 10 AM EST" in July is, read literally, an hour away from a New York clock. Writing "Eastern Time" or the city name avoids all of this, and the same problem exists across countries, covered in timezone abbreviation ambiguity.
What to Do Next
Pick the zone you care about and check it against the date. For a full 24-hour table in each zone, see UTC to EST, UTC to CST, UTC to MST and UTC to PST. For any pair of cities, such as New York to Los Angeles or Chicago to London, set the date in the time zone converter. For the places where a state is split, use the maps for Arizona, Texas, Indiana, Tennessee and Florida. The dates the clocks change each year are on the daylight saving time 2026 page.
Related Articles
- EST to IST Converter: every hour of the day converted for both seasons, with the overlap windows.
- Daylight Saving Time 2026: When Does It Start and End?: the 2026 dates and the weeks when the gap between countries moves.
- DST Rules by Country: The Complete Guide: how US-style DST compares with the rest of the world, including countries that have abolished it.
- How to Calculate Time Difference Between Two Countries: the method for any city pair, including the US zones explained here.