UTC vs GMT: What's the Difference?
UTC vs GMT: What's the Difference?
UTC (Coordinated Universal Time) and GMT (Greenwich Mean Time) are often used interchangeably, but there are important differences.
GMT (Greenwich Mean Time)
GMT is the mean solar time at the Royal Observatory in Greenwich, London. It was the world time standard before UTC.
UTC (Coordinated Universal Time)
UTC is the primary time standard used worldwide. It is based on International Atomic Time (TAI) with occasional leap seconds to stay synchronized with Earth's rotation.
Key Differences
| Feature | UTC | GMT |
|---|---|---|
| Basis | Atomic clocks | Earth's rotation |
| Precision | Extremely precise | Less precise |
| Leap seconds | Yes | N/A |
| Usage | Technical standard | Common reference |
Which Should You Use?
For technical purposes (programming, databases), always use UTC. For casual conversation, both are acceptable. MeetZone uses UTC as the internal reference and converts to local times for display.