How Is UTC Determined and Maintained?
UTC (Coordinated Universal Time) is maintained by the BIPM (Bureau International des Poids et Mesures) in Paris, using data from over 400 atomic clocks in more than 50 countries.
The Atomic Clock Foundation
Atomic clocks measure time using the vibration of cesium-133 atoms. One second is defined as exactly 9,192,631,770 oscillations of a cesium-133 atom. This is so precise that atomic clocks lose less than 1 second every 300 million years.
How UTC Is Calculated
Leap Seconds
| Year | Leap Seconds Added |
|---|---|
| 1972 | 10 (initial offset) |
| 1973-2016 | 27 more added |
| Total (2026) | 37 seconds |
Who Uses UTC?
- Aviation (Zulu time)
- Internet (NTP servers sync to UTC)
- GPS satellites (broadcast UTC)
- Financial markets (trade timestamps)
- Scientific research
Quick Answer
UTC is maintained by the BIPM using 400+ atomic clocks worldwide. It's based on cesium atom oscillations and adjusted with leap seconds to stay aligned with Earth's rotation.
