CET vs GMT time zone comparison

How CET and GMT compare

Central European Time runs one hour ahead of Greenwich Mean Time, the gap between London and the entire western European continent. Paris, Berlin, Madrid, Rome, Brussels, Amsterdam, Warsaw, Stockholm, Copenhagen, and Zurich all sit on CET in winter. The UK and Ireland sit on GMT. Both zones observe daylight saving on the same dates (last Sunday of March, last Sunday of October), so the one-hour gap is constant year-round; CET becomes CEST and GMT becomes BST simultaneously, and the offset never changes. For a London-based team coordinating with Paris or Berlin, the day starts essentially together: 9 AM London is 10 AM Paris, and everyone is at their desk. Lunch happens at the same moment (12 PM or 1 PM local). The end of day is 6 PM London and 7 PM Paris, by which point Paris is checking out a little later than London. The practical implication is that London-CET coordination is the easiest cross-zone work in Europe. Calls can land any time during the day with minimal friction, and the only trap is forgetting which direction the one-hour gap runs (London is behind; CET is ahead). A 10 AM London call is 11 AM Berlin; never the other way around.

Working-hour overlap

Almost the entire working day overlaps. 9 AM to 5 PM London (10 AM to 6 PM CET) is the shared window, with no meaningful constraint.

When to schedule

Default to whatever lands cleanly in both sides' working day. 10 AM London (11 AM Paris) is the safest standing slot. For end-of-day reviews, 4 PM London (5 PM Paris) catches both sides before commute time. Avoid scheduling at 9 AM Paris (8 AM London) because the UK side has not yet warmed up. The one-hour gap is small enough that many teams treat London and continental Europe as effectively one zone — which works until somebody books a 9 AM Brussels meeting and three London attendees miss the first 15 minutes because they treated it as a 9 AM London call.

Notable context

London (LSE) and Frankfurt (DAX) are the two largest European financial markets, and the two trading sessions overlap for the bulk of the day. London opens at 8 AM GMT, Frankfurt at 9 AM CET (which is the same instant), and both close at 4:30 PM GMT / 5:30 PM CET. EU regulatory coordination (Brussels, Strasbourg) operates on CET, so London-based firms with EU compliance teams run regular Brussels calls in the early afternoon London time (3 PM London is 4 PM Brussels). Since Brexit, the regulatory coordination has become more frequent, not less, and the corridor is heavily trafficked.