GMT Converter
A time zone, not a global standard
GMT is the time kept at the Royal Observatory in Greenwich, and Britain’s winter zone specifically — not a universal reference the way UTC is, even though the two names get used interchangeably in everyday speech.
Where the confusion usually comes from
In the northern winter, GMT and UTC read the same, so using either name causes no real problem. The trouble starts in summer, when Britain moves to British Summer Time (UTC+1) but people keep calling it GMT out of habit — a document written that way in July is effectively an hour out.
Questions people ask
Does GMT ever change for daylight saving?
GMT itself doesn’t shift, but Britain leaves it each spring for British Summer Time, so ‘GMT’ stops describing the UK’s actual local time for that half of the year.
Should I use GMT or UTC for something that must mean the same instant everywhere?
UTC — it never shifts for any country’s daylight saving, which is exactly the property you want for something that has to be unambiguous.