Zulu Decoder

Offsets follow each zone's daylight saving rules for the date you enter, so 22 July and 22 January give different answers. On the spring-forward day one clock hour never happens; on the fall-back day one clock hour happens twice. Enter a time inside either window and a line above the strips says which instant was used.

Sources

Zulu and the four-figure clock

The Federal Aviation Administration (FAA) uses Coordinated Universal Time (UTC) for all operations, and the term Zulu may be used to denote it. On the 24-hour clock the hour is the first two figures and the minutes are the last two — which is why the headline reads as four digits and a Z. Aeronautical Information Manual (AIM) 4-2-12, Time Aeronautical Information Publication (AIP) GEN 3.4

Which zones exist, and where they end

The Department of Transportation (DOT) oversees standard time. Nine zones were established by the Standard Time Act of 1918 as amended by the Uniform Time Act of 1966, and their geographic limits are written out in Title 49, Part 71 of the Code of Federal Regulations (CFR). This page covers the four that cover the contiguous states. 49 CFR Part 71, Standard Time Zone Boundaries Bureau of Transportation Statistics (BTS), history of U.S. time zones

Daylight saving dates

Daylight saving time runs from 2 a.m. on the second Sunday in March to 2 a.m. on the first Sunday in November. For 2026 that is 8 March to 1 November. Hawaii, most of Arizona, American Samoa, Guam, Puerto Rico and the U.S. Virgin Islands do not observe it, which is why none of them appear here. National Institute of Standards and Technology (NIST), daylight saving time rules U.S. Naval Observatory, U.S. time zones

Where the offsets come from

Every conversion on this page reads your browser's copy of the Internet Assigned Numbers Authority (IANA) Time Zone Database, the public-domain record of each zone's offset and daylight saving history. Nothing here is hard-coded, so the page tracks the rules as they are amended. IANA Time Zone Database

A change now pending

H.R. 139, the Sunshine Protection Act, would make daylight saving time permanent. The House of Representatives passed it on 14 July 2026 and it is now before the Senate. If it becomes law, the time zone database is updated and this page follows it without any edit. Congress.gov, H.R. 139

Legislative status checked 22 July 2026