The six zones of the 50 states, from east to west, are Eastern, Central, Mountain, Pacific, Alaska and Hawaii-Aleutian. Neighboring zones are one hour apart, and the whole run is UTC-5 to UTC-10 in winter. The territories with permanent residents bring the count of distinct offsets to nine.
This guide gives the offsets, the gaps between zones, the daylight saving dates for 2026 and 2027, and the places where the pattern breaks. All offsets and dates are computed from the IANA time zone database (version 2025b, the copy bundled with Node 22) and hold for 2026 and 2027. The IANA database lists individual zones and does not itself say how many "US time zones" there are, so the counts here are ours: the number of distinct standard offsets in use.
The US time zones at a glance#
UTC (Coordinated Universal Time) is the shared reference clock that never follows the seasons (UTC vs GMT: What Is the Difference and Which Should You Use?). A zone's offset says how far its clocks sit from it. The offsets here are for January 15 and July 15, 2026.
| Zone | Winter name (offset) | Summer name (offset) | Example place |
|---|---|---|---|
| Atlantic | AST (UTC-4) | same all year | Puerto Rico, US Virgin Islands |
| Eastern | EST (UTC-5) | EDT (UTC-4) | New York |
| Central | CST (UTC-6) | CDT (UTC-5) | Chicago |
| Mountain | MST (UTC-7) | MDT (UTC-6) | Denver |
| Pacific | PST (UTC-8) | PDT (UTC-7) | Los Angeles |
| Alaska | AKST (UTC-9) | AKDT (UTC-8) | Anchorage |
| Hawaii-Aleutian | HST (UTC-10) | same all year in Hawaii | Honolulu |
| American Samoa | UTC-11 | same all year | Pago Pago |
| Chamorro | UTC+10 | same all year | Guam, Northern Mariana Islands |
Counting only the 50 states gives six zones, from UTC-5 to UTC-10. In summer the count of offsets in use rises to seven, because the western Aleutian Islands (Adak) stay an hour behind Alaska time all year and so sit at UTC-9 while Honolulu stays at UTC-10 (How Many Time Zones Are There? 24 on Paper, 39 in 2026 counts the world). Adding Puerto Rico, the US Virgin Islands, American Samoa, Guam and the Northern Mariana Islands brings in UTC-4, UTC-11 and UTC+10, which makes nine offsets. The zone names in the table are the common ones; official lists may group or name the territories differently. The IANA data also lists Wake Island, one of the US Minor Outlying Islands, at UTC+12, so a count of "US time zones" depends on which places you include.
The boundaries are not straight lines of longitude. The Standard Time Act of 1918 put US zones into federal law and left the limits to the Interstate Commerce Commission, which was to weigh the convenience of commerce and the railroads' junction and division points, as the text of the law reproduced by WebExhibits describes it. That is one reason the lines bend. The full story is in How Time Zones Were Born: Railways, Telegraphs and the Day of Two Noons and in a Library of Congress history.
How far apart the zones are#
Count hours from New York. Going west, subtract; going east, add. Between the zones that observe daylight saving (Eastern, Central, Mountain, Pacific and Alaska), the gaps stay the same all year, because they all change on the same dates. Arizona, Hawaii and the territories are covered below.
| Place (zone) | Behind New York | When it is 2:00 p.m. in New York |
|---|---|---|
| Chicago (Central) | 1 hour | 1:00 p.m. |
| Denver (Mountain) | 2 hours | 12:00 noon |
| Los Angeles (Pacific) | 3 hours | 11:00 a.m. |
| Anchorage (Alaska) | 4 hours | 10:00 a.m. |
These rows hold on January 15 and on July 15, 2026. To go from Pacific to Eastern, add 3 hours: 9:00 a.m. in Los Angeles is noon in New York. From Mountain to Central, add 1: 9:00 a.m. in Denver is 10:00 a.m. in Chicago and 11:00 a.m. in New York.
Daylight saving in the US: dates and who skips it#
Under federal law (15 U.S.C. § 260a), daylight saving time starts at 2:00 a.m. on the second Sunday in March and ends at 2:00 a.m. on the first Sunday in November. The Congressional Research Service has a report on daylight saving time for further reading. That rule gives these dates for the next two years:
| Year | Clocks go forward | Clocks go back |
|---|---|---|
| 2026 | Sunday, March 8 | Sunday, November 1 |
| 2027 | Sunday, March 14 | Sunday, November 7 |
On Friday, October 9, 2026 (when this guide was last checked), the Eastern, Central, Mountain, Pacific and Alaska zones are all on daylight time, which is UTC-4 down to UTC-8, and they fall back on November 1. If the law changes, the dates change with it; When Do the Clocks Change? Daylight Saving Dates for 2026 and 2027 covers other regions and How Daylight Saving Time Works, Why It Exists and Who Still Uses It explains the mechanism.
Each zone switches at 2:00 a.m. by its own clock, so the change rolls across the country from east to west. For a few hours on those two Sundays the usual gaps are off:
- March 8, 2026. Eastern switches at 07:00 UTC, Central at 08:00, Mountain at 09:00, Pacific at 10:00 and Alaska at 11:00. From 07:00 to 08:00 UTC, New York is already on EDT at 3:30 a.m. while Chicago is still on CST at 1:30 a.m., a gap of 2 hours instead of 1. New York and Los Angeles are 4 hours apart, not 3, from 07:00 to 10:00 UTC, which is 3:00 a.m. to 6:00 a.m. Eastern.
- November 1, 2026. The switches run from 06:00 UTC (Eastern) to 10:00 UTC (Alaska). From 06:00 to 07:00 UTC, New York is on EST while Chicago is still on CDT, so both clocks show the same time, such as 1:30 a.m. at 06:30 UTC.
Outside those early hours, the usual gaps hold.
Arizona, Hawaii and the territories keep one clock all year#
Federal law lets a state exempt itself from daylight saving time, and Hawaii and most of Arizona do not change their clocks. The Navajo Nation, which reaches into Arizona, does observe daylight saving time; the IANA notes label the Phoenix zone "MST - AZ (except Navajo)". For these places the gap to New York is not fixed:
| Place | Offset all year | Behind New York in January | Behind New York in July |
|---|---|---|---|
| Phoenix, Arizona | UTC-7 | 2 hours | 3 hours |
| Honolulu, Hawaii | UTC-10 | 5 hours | 6 hours |
| Puerto Rico, US Virgin Islands | UTC-4 | 1 hour ahead | same time |
| American Samoa | UTC-11 | 6 hours | 7 hours |
| Guam, Northern Mariana Islands | UTC+10 | 15 hours ahead | 14 hours ahead |
Phoenix shows how a fixed clock drifts against its neighbors. In winter it matches Denver (UTC-7) and is an hour ahead of Los Angeles. In summer Denver moves to UTC-6, and Phoenix ends up on the same clock as Los Angeles. Noon in New York on July 15, 2026 is 9:00 a.m. in Phoenix.
The IANA data shows no clock change in 2026 or 2027 for Puerto Rico, the US Virgin Islands, American Samoa, Guam or the Northern Mariana Islands.
States with more than one zone#
Some states have a boundary through them, so "what time is it in Indiana?" has no single answer. These examples come from the regional notes in the IANA database; the list is not a complete census. Texas, Florida, Kentucky, Tennessee, Kansas, Nebraska and the Dakotas also have a boundary through them and are not listed here.
| State | What the IANA notes show |
|---|---|
| Michigan | Detroit is Eastern. Menominee, on the Wisconsin border, is Central, one hour behind. |
| Indiana | Indianapolis is Eastern. Tell City (Perry County) and Knox (Starke County) are Central, one hour behind. |
| Idaho and Oregon | The zone for Boise is described as Mountain Time for southern Idaho and eastern Oregon. Northern Idaho and most of Oregon are on Pacific time, an hour behind. |
| Alaska | Anchorage and most of the state use Alaska time. The western Aleutian Islands use Hawaii-Aleutian time: UTC-10 in winter, UTC-9 in summer. |
Check the place, not the state. A Timelive city page or the time zone converter shows the clock for the city you pick. For anything with legal force, such as a filing deadline or a flight, confirm with the official source for that location.
Scheduling across US time zones#
- Name the zone and the date. "Wednesday, July 15, 2:00 p.m. ET" works in any month. Use EST or PST only when you have checked which one applies that day.
- Find the shared window. For four mainland zones, noon to 5:00 p.m. ET is 9:00 a.m. to 2:00 p.m. PT, a five-hour stretch where everyone is inside a 9-to-5 day. It does not move with the seasons.
- Treat Arizona, Hawaii and the territories separately. Their gap to the mainland shifts at each clock change, as the table above shows.
- Avoid early Sunday on the switch dates, and expect gaps to places outside the US to shift on other dates. How to Schedule a Meeting Across Time Zones: A 6-Step Checklist covers recurring meetings, and How to Convert Time Between Time Zones, Step by Step (With Examples) walks through converting step by step.
Frequently asked questions
How many time zones does the US have?
By standard clock settings, the 50 states use six, from UTC-5 (Eastern) to UTC-10 (Hawaii-Aleutian). The 48 contiguous states use four of them: Eastern, Central, Mountain and Pacific. Including the territories with permanent residents gives nine offsets, adding UTC-4, UTC-11 and UTC+10. The count depends on what you include: the IANA time zone database also lists Wake Island at UTC+12, which would make ten.
What is the time difference between PST and EST?
Eastern time is 3 hours ahead of Pacific time. To convert PST to EST, add 3 hours: 9:00 a.m. Pacific is noon Eastern. The gap is the same in July, between PDT and EDT.
It goes wrong only when a label does not match the season. Read literally, "PST" in July is UTC-8 and "EDT" is UTC-4, a 4-hour gap, so write PT and ET to be safe.
Do all US states use daylight saving time?
No. Federal law lets a state exempt itself, and Hawaii and most of Arizona stay on standard time all year. The Navajo Nation, which extends into Arizona, does observe daylight saving time. Puerto Rico, the US Virgin Islands, American Samoa, Guam and the Northern Mariana Islands also show no clock change in the IANA data for 2026 and 2027.
Everywhere else, clocks go forward on the second Sunday in March and back on the first Sunday in November.
What time zone is Arizona in?
Most of Arizona uses Mountain Standard Time, UTC-7, all year. In winter that equals Denver. In summer Denver moves to UTC-6 and Arizona has the same clock as Los Angeles. Phoenix is therefore 2 hours behind New York in winter and 3 hours behind in summer. The Navajo Nation part of Arizona does change its clocks.
Sources and further reading
- Daylight Saving Time (DST) — Congressional Research Service
- Original U.S. Law (Standard Time Act of 1918) — WebExhibits
- Whose Time is it Anyway? A Brief History of Standardized Time Zones in the United States — Library of Congress