Coordinated Universal Time (abbreviated to UTC) is the primary time standard by which the world regulates clocks and time. World time is added to or subtracted from the time at 0° longitude, which is not adjusted for daylight saving time.

Time Zone Time Examples Standard Time Daylight Time Zone
Hawaii-Aleutian Time 06 AM–11 AM HST (UTC–10:00) HST (UTC–10:00) Zone W
Alaska Time 07 AM–12 PM AKST (UTC–09:00) AKDT (UTC–08:00) Zone V
Pacific Time 08 AM–01 PM PST (UTC−08:00) PDT (UTC−07:00) Zone U
Mountain Time 09 AM–02 PM MST (UTC−07:00) MDT (UTC−06:00) Zone T
Central Time 10 AM–03 PM CST (UTC−06:00) CDT (UTC−05:00) Zone S
Eastern Time 11 AM–04 PM EST (UTC−05:00) EDT (UTC−04:00) Zone R
Atlantic Time 12 PM–05 PM AST (UTC–4:00) AST (UTC–4:00) Zone Q

Primary U.S. Time Zones

Pacific Time: California, Washington, Oregon, Nevada, Idaho

Mountain Time: Arizona (No Daylight Savings outside of Navajo Nation), Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Texas, Utah, Wyoming

Central Time: Alabama, Arkansas, Florida, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, North Dakota, Oklahoma, South Dakota, Tennessee, Texas, Wisconsin

Eastern Time: Connecticut, Florida, District of Columbia, Delaware, Georgia, Indiana, Kentucky, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Maryland, Virginia, West Virginia

USA Timezone Map

There are four primary time zones across the contiguous United States. Some United States Minor Outlying Islands are outside the time zones. Alaska is 1 hour behind Pacific Time and Hawaii, depending upon Daylight Saving Time, is 2 hours behind. Bermuda and the Caribbean Islands, including Puerto Rico, observe Atlantic Standard Time without observing Daylight Saving Time.

Daylight Saving Time

Daylight saving time (DST) begins on the second Sunday in March and ends on the first Sunday in November. Arizona and Hawaii use standard time throughout the year. Clocks are set ahead one hour at 2 AM on the following start dates and set back one hour at 2 AM on these ending dates:

Year Start date Ending date
2019 March 10 November 3
2020 March 8 November 1
2021 March 14 November 2
2022 March 13 November 6
2023 March 12 November 5
2024 March 10 November 3
2025 March 9 November 2

Australia has 5 standard time zones that honor separate daylight savings times plus 2 locations (Broken Hill and Eucla) with fractional hour differences.