UTC and World Time Basics
What Coordinated Universal Time is, how it differs from GMT, and how to use it for time differences.
UTC (Coordinated Universal Time) is the global time reference. It does not observe daylight saving and does not change with seasons. Local times are expressed as "UTC plus or minus hours" — Beijing is UTC+8; New York is UTC-5 in standard time.
UTC vs GMT
GMT (Greenwich Mean Time) originated at the Royal Observatory in Greenwich, UK. In everyday use GMT and UTC are treated as equivalent. Technically UTC is based on atomic clocks and is more precise. For travel and business, the difference is negligible.
Why UTC matters
- Aviation, shipping, the internet, and finance need one unambiguous baseline
- DST affects local time only — UTC stays stable for logs and server timestamps
- Distributed teams often agree on deadlines in UTC to avoid confusion
- IANA time zones describe each region as a UTC offset with DST rules
Quick conversion
On our home page or Countries list, each nation shows its current UTC offset. If Beijing is UTC+8 and London is UTC+1 (winter), Beijing is 7 hours ahead. When London is 12:00, Beijing is 19:00. Use the Convert with any date/time for automatic DST handling.
UTC and DST
UTC has no daylight saving, but local offsets change in many countries. New York moves from UTC-5 to UTC-4 in summer. Saying "New York is UTC-5" is only true during standard time. See the DST Guide guide for details.