Published October 12, 2026 · Updated October 12, 2026
The short answer: UTC
The International Space Station runs on Coordinated Universal Time (UTC), the same as the old Greenwich Mean Time (GMT). It doesn't observe daylight saving time, and it doesn't change with whatever the station happens to be flying over. If it's 18:00 UTC right now, it's 18:00 on the ISS, whether the station is over Australia, the Pacific or Madrid.
To find out what time it is up there from the US, add hours to your clock: four in the Eastern time zone in summer and five in winter, plus one more for each time zone you go west. Here's how that works out at noon:
| If your clock says 12:00 noon… | On the ISS it's… |
|---|---|
| Eastern, summer (EDT, UTC−4) | 16:00 |
| Eastern, winter (EST, UTC−5) | 17:00 |
| Central, summer (CDT, UTC−5) | 17:00 |
| Central, winter (CST, UTC−6) | 18:00 |
| Mountain, summer (MDT, UTC−6) | 18:00 |
| Mountain, winter (MST, UTC−7) | 19:00 |
| Pacific, summer (PDT, UTC−7) | 19:00 |
| Pacific, winter (PST, UTC−8) | 20:00 |
Alaska is on UTC−8 in summer (AKDT) and UTC−9 in winter (AKST). Hawaii stays on UTC−10 (HST) all year with no clock change, and most of Arizona keeps Mountain Standard Time (UTC−7) year-round. In the UK, ISS time matches the clock in winter (GMT) and is one hour behind it in summer (BST).
In 2026, the US falls back to standard time on Sunday, November 1 (the UK and the EU change a week earlier, on October 25). From that day on, the station is five hours ahead of Eastern time instead of four, and eight hours ahead of Pacific time instead of seven.
Why UTC
The ISS is run jointly by control centers in Houston, Moscow, Munich (the European Space Agency's is in Oberpfaffenhofen), Tsukuba and Montreal, among others. Each one has its own time zone. Picking any one of them would have forced all the others to convert times constantly.
UTC is a neutral reference that aviation and most technical systems already use. It also falls roughly halfway between Houston and Moscow, the two main control centers, which spreads the inconvenience around: neither has to work in the middle of the night while the crew is awake.
A typical day on board
The crew's schedule is planned down to the minute from the ground. It varies with the tasks at hand, but a typical workday looks roughly like this, always in UTC:
- Around 06:00: wake-up, washing up and breakfast. That's 2 a.m. Eastern time in summer.
- First thing: a daily planning conference with the control centers in Houston, Moscow, Europe and Japan to go over the day's plan.
- Morning and afternoon: experiments, maintenance and about two hours of exercise, which is mandatory to slow the loss of muscle and bone.
- Early evening: another conference with the ground to wrap up the day.
- Around 21:30: lights out, followed by eight and a half hours of rest.
Saturdays usually go to cleaning and catching up on chores, and Sundays are mostly free. When a docking or a spacewalk falls at an awkward hour, the whole schedule shifts for a few days so the crew goes in well rested. We cover the daily routine in more detail in life on the ISS.
Sleeping with 16 sunrises a day
The station circles the Earth about every 92 minutes, so the Sun rises and sets outside its windows about 16 times a day. Without a fixed schedule, the body wouldn't know when it's night. To help the body clock:
- Each crew member has a small private cabin, about the size of a phone booth, with a sleeping bag strapped to the wall.
- The module windows are covered with shutters during the rest period.
- The US segment is lit with LED lights that can change tone: bluer to stay alert and warmer before bedtime.
Even so, sleeping well up there isn't easy. The noise from the fans, which never shut off because without gravity the air doesn't circulate on its own, and the lack of any sense of lying down mean that many astronauts sleep less than planned.
Is it day or night on the ISS right now? The map in our tracker shows you live, along with the minutes left until the next orbital sunrise or sunset. It has nothing to do with the clock: it's about whether the station is in sunlight or in Earth's shadow.
And the times we show you
Although the station lives on UTC, the tracker shows every time, from passes and countdowns to launches, in your device's time. Whatever time zone your phone is set to, there's nothing to convert. The only thing to watch out for is the week the clocks change, if you note down a pass in advance. To make sense of the rest of the details for each pass, see our guide on how to read a pass.
Frequently asked questions
What time is it on the ISS?
UTC, the equivalent of the old Greenwich Mean Time. In the Eastern time zone, the ISS is four hours ahead of your clock in summer and five in winter; in the Pacific time zone, seven and eight.
Why does the ISS use UTC?
Because it's run by control centers in several countries with different time zones. UTC is a neutral reference, it's used in aviation and technical systems, and it falls halfway between Houston and Moscow.
Does the ISS observe daylight saving time?
No. The station uses UTC all year round. What changes is the gap between ISS time and US time when clocks spring forward or fall back; in 2026, the US falls back on November 1.
How do astronauts sleep with 16 sunrises a day?
They follow a fixed schedule on UTC, sleep in private cabins, cover the module windows and use lights that change tone to help their body clocks.
What time do astronauts get up?
On a normal day, around 06:00 UTC, and lights go out around 21:30 UTC. The schedule shifts when dockings or spacewalks happen at unusual hours.
Is it day or night on the ISS right now?
Check the map