Regardless of your current time zone, it makes more sense to have a universal standard time so you can communicate with others about time while avoiding time zone confusion. Zulu Time is the standard time used by pilots, the military, and others operating on a 24-hour clock.
What Is Zulu Time?
Zulu Time is the aviation and military name for Greenwich Mean Time (GMT), which is the current time at 0 degrees longitude. This corresponds to the current time in Greenwich, England — a section of London. It’s also sometimes referred to as Coordinated Universal Time (UTC).
If you work in a profession that crisscrosses time zones regularly, then it makes no sense to keep up with the various local times. Instead, you’d use Zulu Time as a universal frame of reference — especially when others may not know your time zone.
To avoid confusion, keep these points in mind:
- UTC is not a time zone, but a time standard.
- GMT is a time zone that never changes. But, not all countries that fall within this time zone use GMT year-round.
- The United Kingdom, for example, uses GMT except during the summer months when it uses British Summer Time (BST) — one hour ahead of GMT.
- To clarify, Zulu Time, GMT, and UTC all keep the same time.
How To Use Zulu Time
Converting to Zulu Time involves a two-step process:
- First, convert your local time to 24 hour time.
- Then add an offset based on your local time zone.
If you’re in Saint Louis, Mo., and it’s 5:30 p.m., what’s the Zulu Time?
- First, add 12 hours to 5:30 to determine your 24-hour time: 17:30 hours.
- Next, use a time conversion table to find the appropriate offset. In the Central Standard Time zone (Saint Louis local time) you must add six hours for standard time, but five hours for daylight-saving time. If it’s September, you’d add five hours to convert to 22:30 Zulu Time.
The Earth rotates around the sun and, at night, the sun shines on the opposite side of the planet. Time measurement, therefore, travels with the line between daylight and darkness as it crosses the Earth.
When it’s 11 a.m. in Greenwich, England, it’s 6 a.m. in Ann Arbor, Mich. and only 3 a.m. in San Jose, Calif. Times also shift with seasonal clock adjustments, but the same concept still applies. When it’s 3 p.m. in Saint Louis, Mo., it’s only 2 p.m. in Santa Fe, N.M.
The military communicates missions based on time so it uses Zulu Time to avoid confusion. When it’s 11:00 Zulu Time in Saint Louis, Mo., it’s 11:00 Zulu Time at every other point on Earth — eliminating any potential time zone confusion.
Frequently Asked Questions
How do you calculate Zulu Time?
Start by converting your local time to 24-hour time and then add the difference between your current time zone and GMT. This will give you your current Zulu Time.
What is Military Zulu Time?
Military Zulu Time is the same as Zulu Time.
What’s the difference between GMT and Zulu Time?
There’s no difference between GMT and Zulu Time except that Zulu Time is always written in Military Time.
What’s the difference between Military Time and Zulu Time?
Military Time uses a 24-hour clock to keep time. While Zulu Time also does so, it always aligns with the local time in the GMT time zone.