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

Return flights

12 Sep - 22 Sep	Thai AirAsia
14 Sep - 21 Sep	SriLankan Airlines
13 Sep - 21 Sep	SriLankan Airlines
01 Sep - 14 Sep	IndiGo
04 Sep - 12 Sep	IndiGo
05 Sep - 14 Sep	IndiGo
12 Sep - 21 Sep	IndiGo
11 Sep - 14 Sep	IndiGo
26 Sep - 08 Oct	Air India
05 Sep - 16 Sep	Air India
30 Sep - 28 Oct	Air India
28 Sep - 08 Oct	Air India
22 Sep - 06 Oct	Air India
22 Sep - 03 Oct	Air India
21 Sep - 02 Oct	Air India
22 Sep - 04 Oct	Air India
21 Sep - 04 Oct	Air India
21 Sep - 03 Oct	Air India
26 Sep - 10 Oct	Air India
04 Sep - 12 Sep	Singapore Airlines	direct

Also check the deals for one-way flights from Singapore 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 Singapore to Kathmandu in September from $409

Return flights