What Time Zone Am I In?

What time zone am I in right now?

Your time zone is shown at the top of this page as soon as it loads: the IANA name (such as America/Chicago), the everyday name (Central Time), the abbreviation (CST or CDT), the UTC offset, whether daylight saving time is in effect, and a live clock. It is read from the time zone your phone or computer is set to, through the browser's built-in Intl API, so no location permission is needed and nothing is sent anywhere.

That setting is usually right, because most devices set it automatically. It can be wrong in a few situations, and that is what the Check with GPS button is for: it takes your physical position and tests it in your browser against time zone polygons (the open-source tz-lookup data, simplified to about 1 km), then tells you if your device and your location disagree.

• You set the zone by hand, or turned off automatic time zone, and then traveled.
• You are near a zone line. Phones often take the zone from the cell network, and a tower across the line can win (see below).
• A privacy mode such as Tor Browser or Firefox's fingerprinting protection reports UTC instead of your real zone.
• You use a VPN. A VPN does not change your device clock, so this page is unaffected, but websites that guess your zone from your IP address will show the VPN server's zone instead.

Why your phone can show the wrong time zone near a border

Phones rarely run their own point-in-polygon check. Their modem listens for the time zone broadcast by the cell network (the NITZ protocol), and radio signals carry across rivers and flat farmland for ten miles or more. If a tower on Central Time gives a stronger signal than a tower on Eastern Time, the phone adopts Central Time even though you are standing in Eastern.

This happens along the Ohio River between Indiana and Kentucky, near Gary, Indiana on Lake Michigan, and on the Georgia-Alabama line, where Phenix City, Alabama unofficially keeps Eastern Time to match Columbus, Georgia across the river. A GPS check evaluates your actual coordinates instead of the tower's.

How to find the time zone of any city or ZIP code

State or country borders are not enough to tell the time zone of an address: thirteen US states are split between two zones, and a few counties are split too. The search box above handles any place in three steps:

1. Type a city, street address, landmark or five-digit US ZIP code, or click a point on the map. Places are geocoded with Photon (built on OpenStreetMap); ZIP codes use the Census Bureau's ZCTA center point, with the geocoder as a fallback.
2. The point is matched against time zone polygons (tz-lookup) to get its IANA zone name, for example America/Denver.
3. Your browser's time zone data then supplies the local time, UTC offset, abbreviation and whether daylight saving time is in effect.

A ZIP code is a mail route, not an area with a legal boundary, so a few ZIP codes along a zone line cover parts of two zones. If the answer matters (a delivery window, a court deadline), search the full street address. To compare two places, use the time difference calculator.

Time zones of major cities

US time zones by state

The contiguous 48 states use four time zones (Eastern, Central, Mountain and Pacific). Counting Alaska, Hawaii and the territories, federal law recognizes nine standard time zones from the Caribbean to Micronesia. See them all on the US time zone map.

Time zone of every state

States marked split have more than one official zone, so look up the exact address or ZIP code above when you are near the line.

Who draws time zone lines?

In theory each zone is a 15-degree band of longitude, one hour of the Earth's rotation. In practice US zone lines are legal boundaries under the Standard Time Act of 1918 and the Uniform Time Act of 1966 (15 U.S.C. §§ 260–267). Only the U.S. Department of Transportation can move them, under 49 CFR Part 71, and its test is “the convenience of commerce”: where schools, hospitals, TV markets and commuters look. That is why the lines follow county borders and rivers rather than meridians.

Arizona, the Navajo Nation and the Hopi Reservation

Arizona opted out of daylight saving time in 1968 and stays on Mountain Standard Time (UTC−7) all year. The Navajo Nation, which spans northeastern Arizona, northwestern New Mexico and southeastern Utah, does observe daylight saving time so its offices stay in step across the three states. The Hopi Reservation, surrounded by the Navajo Nation, follows Arizona and does not. Driving west on I-40 from Gallup in July, your clock does not change at the state line (you enter the Navajo Nation on UTC−6); it drops an hour only after you leave the reservation.

Counties split between two time zones

Most counties sit in one zone, but the boundary descriptions in 49 CFR Part 71 cut through a handful of them:

• Cherry County, Nebraska: the east, including the county seat of Valentine, is Central; the west is Mountain.
• Malheur County, Oregon: the area around Ontario keeps Mountain Time with the Boise market; the rest of the county is Pacific.
• Elko County, Nevada: West Wendover was moved to Mountain Time to match Wendover, Utah (64 FR 56707).
• Idaho County, Idaho: the Salmon River is the line; south of it is Mountain, north of it Pacific.
• McKenzie County, North Dakota: Central, except the southwestern corner, which is Mountain.

The full list is in our study of split-time-zone counties.

Daylight saving time

In the United States, daylight saving time begins on the second Sunday in March at 2:00 a.m. local time (clocks jump to 3:00 a.m.) and ends on the first Sunday in November at 2:00 a.m. (clocks fall back to 1:00 a.m.), a schedule set by the Energy Policy Act of 2005. Hawaii, most of Arizona, Puerto Rico, the US Virgin Islands, Guam, the Northern Mariana Islands and American Samoa do not change their clocks. The device panel above shows the date of your next clock change.

Europe changes on the last Sunday of March and October, so for a few weeks each spring and autumn New York is four hours behind London instead of five. In the southern hemisphere the seasons are reversed: Sydney moves its clocks forward in October and back in April.

Under 15 U.S.C. § 260a a state may stay on standard time all year (as Hawaii and Arizona do), but it cannot adopt permanent daylight saving time without an act of Congress.

What do UTC−5, EST and America/New_York mean?

The same time zone has three kinds of label. The UTC offset (UTC−5) says how far the clock is from Coordinated Universal Time right now. The abbreviation (EST in winter, EDT in summer) is the everyday name. The IANA identifier (America/New_York) names a region in the time zone database that software uses, and records every offset and daylight saving rule that region has had since 1970.

Abbreviations are handy but ambiguous, which is why software and this tool lead with IANA names:

• CST can mean Central Standard Time (UTC−6), China Standard Time (UTC+8) or Cuba Standard Time (UTC−5).
• IST can mean India (UTC+5:30), Irish (UTC+1) or Israel Standard Time (UTC+2).
• AST can mean Atlantic Standard Time (UTC−4) or Arabia Standard Time (UTC+3).

Different IANA names can share a clock: America/Detroit and America/New_York show the same time today but have different histories. If your GPS result and your device use different names with the same offset, your clock is still right.

Why clock noon is not solar noon

Zones are drawn so that the sun is highest (solar noon) close to 12:00 clock time, but a zone is about 15 degrees wide, so solar noon at its eastern edge comes up to an hour earlier than at its western edge, and daylight saving time shifts it another hour later. The sunrise and sunset calculator gives the exact solar noon for any place.

Accuracy and limitations