AirHint found the following cheapest return flights from Boston (BOS) to Calgary (YYC) in August 2025 (see full year).

Return flights

25 Aug - 29 Aug	Frontier Airlines
24 Aug - 02 Sep	Frontier Airlines
23 Aug - 30 Aug	Spirit Airlines
26 Aug - 28 Aug	jetBlue
20 Aug - 01 Sep	Spirit Airlines
22 Aug - 29 Aug	Spirit Airlines
21 Aug - 28 Aug	Frontier Airlines
20 Aug - 24 Aug	Spirit Airlines
22 Aug - 30 Aug	Frontier Airlines
22 Aug - 31 Aug	Frontier Airlines
22 Aug - 01 Sep	Frontier Airlines
18 Aug - 24 Aug	Frontier Airlines
29 Aug - 02 Sep	Delta
23 Aug - 30 Aug	WestJet	direct
20 Aug - 01 Sep	WestJet	direct
22 Aug - 01 Sep	WestJet	direct

Also check the deals for one-way flights from Boston to Calgary 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 Boston to Calgary in August from $387

Return flights