Zulu time (UTC) converter
Convert a local time to Zulu (UTC) or the other way round for any time zone, and read METAR-style DDHHMMZ time groups.
Runs entirely in your browser
Read a METAR or TAF time group
Uses the time zone data built into your browser, including daylight saving rules. Not for flight planning or navigation: check the official time and NOTAM validity yourself.
How to convert local time to Zulu
- Choose the date and the clock time, and the time zone it is in. The first box starts with your own time zone.
- Choose the zone to show it in: the default is UTC, also called Zulu time or Z.
- Read the converted time and the DDHHMMZ group. To decode a time group from a METAR or TAF, type it in the second section.
How the conversion works
UTC (Coordinated Universal Time) is the international civil time standard maintained by the BIPM and defined in ITU-R Recommendation TF.460. It is written with the suffix Z in aviation, from the military time zone letter Zulu, and in the ICAO time group format DDHHMMZ used by METAR, TAF and SIGMET messages (ICAO Annex 3, WMO No. 306). Local time is UTC plus the zone's offset, which depends on the date because of daylight saving rules.
The page turns the date and clock time you enter into an instant using the offset the zone had at that moment, and then shows the instant in the other zone. This uses the IANA Time Zone Database through your browser's Intl API, the same data used by operating systems. An invalid local time in the hour skipped at the start of daylight saving is moved forward by the gap, and an ambiguous time in the repeated hour uses the first occurrence.
A time group has no month or year, so the tool tries the previous, the same and the next month and keeps the date nearest to the reference date you give (today, UTC, by default), which is how a weather report is normally matched to a calendar. Not for flight planning or navigation.
Questions
What is Zulu time?
Zulu time is Coordinated Universal Time (UTC), written with the letter Z, which is the NATO phonetic name for the military time zone with no offset. Aviation, meteorology and the military use it so that everyone has one clock, with no daylight saving changes.
How do I read a time group such as 081405Z?
The first two digits are the day of the month (08), the next two the hour (14) and the last two the minutes (05), always in UTC, so 081405Z is the 8th day at 14:05 UTC. METAR, TAF and NOTAM times use this form. The month and year are not stated, so the tool picks the one nearest to the reference date.
Is UTC the same as GMT?
For everyday use, yes: the clocks show the same time. Strictly, GMT is a time zone based on the Earth's rotation and UTC is an atomic time scale kept within 0.9 seconds of it with leap seconds. Aviation uses UTC.
Does Zulu time have daylight saving?
No. UTC never changes. A local time zone's offset from UTC changes when its daylight saving starts or ends, which is why a flight schedule is easier to read in UTC.
What happens at a daylight saving change?
When clocks jump forward, one hour of local time does not exist, and the tool moves to the nearest valid time. When clocks go back, one hour happens twice and the tool uses the first one, and tells you.
Where does the tool get its time zone rules?
From your browser's built-in IANA time zone database (the Intl API), so nothing is downloaded. An old browser may have outdated rules for some countries.