現在の GMT 時刻
現在の Unix タイムスタンプ付きのライブ GMT 時計。GMT は UTC+00:00 にあり、実用上はすべて UTC と同等です。
What is GMT?
GMT (Greenwich Mean Time) is the timezone at zero UTC offset, historically defined by the mean solar time at the Royal Observatory in Greenwich, London. It has been used as the international time standard since 1884 and is the basis for UTC.
When GMT differs from UTC
In strict astronomical terms, GMT can vary from UTC by up to 0.9 seconds because Earth's rotation is not perfectly uniform. UTC corrects for this with occasional leap seconds. In practice, software and networking always use UTC — GMT remains in everyday language and HTTP headers.