Istanbul runs on UTC+3 all year. Brussels does not. That is the whole story, and it means the gap between the two cities is never fixed: 1 hour in summer, 2 hours in winter.

Why Istanbul stays put while Brussels moves

Turkey abandoned daylight saving in 2016 and locked the clocks on Turkey Time (TRT, UTC+3). Brussels still follows the EU directive, swinging between Central European Time (CET, UTC+1) in winter and Central European Summer Time (CEST, UTC+2) in summer. The result is a twice-yearly shift that catches people out, especially in the weeks around the change.

When the Brussels, Istanbul gap shrinks and widens

Two Sundays matter.

  • Sunday 29 March 2026 at 02:00 local: Brussels springs forward to CEST (UTC+2). The difference with Istanbul narrows to 1 hour.
  • Sunday 25 October 2026 at 03:00 local: Brussels falls back to CET (UTC+1). The gap widens to 2 hours.

From late March to late October you lose one hour between the cities. The other five months you lose two.

What time is it in Istanbul when it’s 10:00 in Brussels?

Depends on the season. In summer, 10:00 Brussels is 11:00 Istanbul. In winter, 10:00 Brussels is 12:00 Istanbul. Both are workable, but the lunch collision in winter is real.

Best and worst times for a Brussels, Istanbul call

Aim for 09:00 to 11:00 Brussels time. That lands at 10:00 to 12:00 Istanbul in summer, or 11:00 to 13:00 Istanbul in winter, before the midday break.

Avoid 12:00 to 13:30 Brussels time. In summer that pushes into 13:00 to 14:30 Istanbul, right when lunch clears offices. In winter it is worse: 14:00 to 15:30 Istanbul, deep into the afternoon lull.

Is Brussels always 1 or 2 hours behind Istanbul?

Yes. Brussels is always behind. Add 1 hour in summer, 2 hours in winter. Turkish time never changes, so the difference depends entirely on what Brussels is doing. Check the date against the last Sunday of March and the last Sunday of October.

When Brussels next changes relative to Istanbul

Sunday 25 October 2026. Clocks go back to CET and the Istanbul gap jumps from 1 hour to 2 hours. If you have calls the following week, shift them now.