AirHint found the following cheapest return flights from Kolkata (CCU) to Kathmandu (KTM) in September 2025 (see full year).

Return flights

04 Sep - 14 Sep	Air India
09 Sep - 16 Sep	Air India
12 Sep - 17 Sep	Air India
04 Sep - 04 Sep	Air India
19 Sep - 06 Oct	Air India
28 Sep - 05 Oct	Air India
25 Sep - 02 Oct	IndiGo
25 Sep - 03 Oct	Air India
30 Sep - 05 Oct	Air India
29 Sep - 05 Oct	Air India
27 Sep - 30 Sep	Air India
27 Sep - 04 Oct	Air India
22 Sep - 25 Sep	flydubai

Also check the deals for one-way flights from Kolkata to Kathmandu in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Kolkata to Kathmandu in September from 185€

Return flights