Kathmandu is 0.25 hours ahead of Chennai
Best overlap: 8:00 AM to 6:00 PM in Chennai is 8:15 AM to 6:15 PM in Kathmandu.
For a call that suits both sides, look at 8:00 AM to 6:00 PM in Chennai / 8:15 AM to 6:15 PM in Kathmandu. With 10 hours of daily overlap, these two cities are an easy pairing; almost any reasonable hour works.