Time Zone Converter

GMT, BST, and the UK timezone confusion

The UK is one of the few countries whose name for its own timezone , Greenwich Mean Time , is also the global reference point. GMT and UTC are effectively the same offset (UTC+0), but the UK only observes GMT in winter. From the last Sunday in March to the last Sunday in October, the UK moves to British Summer Time (BST, UTC+1). This means that when someone says "let's meet at 10 AM GMT" in July, they almost certainly mean 10 AM BST , which is UTC+1, not UTC+0. The ambiguity causes real scheduling errors.

The US switches its clocks roughly two weeks before the EU does in spring, and one week after the EU in autumn. During those transition windows, the gap between London and New York is temporarily 4 hours rather than the usual 5.

Key UK business timezone overlaps

DST transition edge cases

When the UK clocks change, any recurring meeting scheduled as a fixed local time will shift relative to participants in other countries. A 9 AM London call in winter (UTC+0) becomes a 9 AM BST call in summer (UTC+1) , the same local time but one hour later in UTC. If your counterpart in New York has the call in their calendar as "2 PM EST," they will show up at 2 PM EDT in summer, which is still aligned. But a counterpart in a country that does not observe DST at all (such as the UAE or Japan) will find the call has moved by one hour relative to their local time.

Scheduling across hemispheres

Australia's DST runs from October to April , the opposite of the UK. Sydney is UTC+10 in its winter and UTC+11 in its summer, which is the UK's winter. This means the gap between London and Sydney is smallest (9 hours) in Northern Hemisphere summer and largest (11 hours) in Northern Hemisphere winter. Finding a workable slot is easier to check with a converter than to calculate by hand. For recurring meetings across borders, use this converter alongside the Working Days Calculator to avoid scheduling conflicts on national holidays.