Chronos Guide

UTC vs GMT

UTC and GMT are often used as if they mean the same clock time, but they are not exactly the same concept.

Simple explanation

UTC, or Coordinated Universal Time, is the modern time standard used by computers, aviation, APIs and global scheduling systems. GMT, or Greenwich Mean Time, is historically linked to mean solar time at Greenwich.

When they match

For everyday planning, UTC+0 and GMT usually display the same clock time. That is why people often say GMT when they mean UTC.

When to use UTC

Use UTC for logs, databases, server jobs, timestamps, APIs and anything that must be unambiguous across countries.

When to use GMT

Use GMT when referring to UK winter civil time or when a human audience expects the familiar term. For technical precision, UTC is safer.