About this tool
The UTC Time Converter shows the current Coordinated Universal Time ticking beside your own local clock and offset, then lets you convert any local date and time to UTC or any UTC time back to local. Each conversion is written out in the formats that matter in practice: ISO 8601 with a Z suffix, ISO 8601 with a numeric offset, RFC 2822 as used in email headers, and the Unix timestamp in seconds, each with its own copy button. A reference table lists what time it is right now in about twenty major zones with their current UTC offset and whether daylight saving is in effect. It is aimed at developers reading logs, people scheduling across regions, and anyone who has been told a launch is at '14:00 UTC'.
How it works
UTC is the time standard that all zones are defined against; your browser reports the local offset for any instant, and Intl.DateTimeFormat with a timeZone option reports the offset of any other zone, so no offsets are hard-coded and daylight-saving rules for the chosen date are applied automatically. Converting local to UTC builds a Date from the local wall-clock fields, which the browser resolves to an instant using your zone's rules, then formats that instant with the UTC getters. Converting UTC to local uses Date.UTC on the entered fields and formats the result locally. The ISO 8601 string is YYYY-MM-DDTHH:MM:SSZ where Z means zero offset; the same instant can be written with an explicit offset such as 10:00:00-04:00. The Unix timestamp is milliseconds since 1970-01-01T00:00:00Z divided by 1,000 and floored.
Frequently asked questions
Is UTC the same as GMT?
For everyday purposes yes: both are the time at zero degrees longitude with no daylight-saving adjustment, and clocks showing GMT and UTC agree to within a second. Technically GMT is a time zone based on the Earth's rotation while UTC is an atomic-clock standard kept within 0.9 seconds of it by leap seconds. Aviation, computing, and science use UTC; the United Kingdom uses GMT as the name of its winter time zone.
What does the Z at the end of an ISO 8601 time mean?
Z stands for zero UTC offset, spoken as 'Zulu' in the NATO phonetic alphabet, so 2026-09-13T14:00:00Z is 14:00 UTC exactly. It is equivalent to writing +00:00. A time with no Z and no offset, such as 2026-09-13T14:00:00, is a 'local' time with no zone attached, and different systems will interpret it differently, which is a common source of bugs.
Why does my UTC offset change during the year?
Because your region observes daylight saving time. New York is UTC-5 in winter (EST) and UTC-4 in summer (EDT); London is UTC+0 in winter (GMT) and UTC+1 in summer (BST). UTC itself never changes, which is exactly why it is used as the reference: a log entry stamped 14:00Z means the same instant regardless of where or when it is read.
Which zones have no daylight saving time?
Most of Asia and Africa, including Japan, China, India, Singapore, and South Africa, as well as Arizona (except the Navajo Nation) and Hawaii in the United States, Queensland and Western Australia, and Iceland. Since 2011 Russia and since 2016 Turkey have also kept a fixed offset all year. The table on this page marks each zone's current DST status.