Chennai is 3.5 hours ahead of Zurich
Best overlap: 8:00 AM to 3:00 PM in Zurich is 11:30 AM to 6:30 PM in Chennai.
Shoot for 8:00 AM to 3:00 PM in Zurich; your Chennai colleagues will see that as 11:30 AM to 6:30 PM. The overlap is wide at 7 hours, so you can protect mornings for deep work and still find plenty of meeting time. Don't be caught out by clock changes — Zurich observes daylight saving and Chennai doesn't, so the offset varies by an hour through the year.