AirHint found the following cheapest return flights from Colombo (CMB) to Kathmandu (KTM) in August 2025 (see full year).

Return flights

25 Aug - 05 Sep	Air India
04 Aug - 06 Aug	Air India
07 Aug - 20 Aug	Air India
18 Aug - 27 Aug	Air India
07 Aug - 21 Aug	Air India
14 Aug - 24 Aug	Air India
04 Aug - 13 Aug	Air India
07 Aug - 19 Aug	Air India
07 Aug - 18 Aug	Air India
07 Aug - 15 Aug	Air India
08 Aug - 15 Aug	Air India
30 Aug - 17 Sep	IndiGo
31 Aug - 18 Sep	Air India
24 Aug - 04 Sep	IndiGo
24 Aug - 04 Sep	SriLankan Airlines	direct
31 Aug - 18 Sep	SriLankan Airlines	direct

Also check the deals for one-way flights from Colombo to Kathmandu in August.

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 Colombo to Kathmandu in August from $372

Return flights