Betfair charges Commission only on your net winnings on a market. You do not pay commission on losing bets. How much Commision do I pay? This is how it is calculated: Commission = Net Winnings x Market Base Rate x (100%-Discount Rate).
Betfair Exchange - Change of Minimum Stake to 1 - from 7th February 2024. Please be aware that from the 7thFebruary, the minimum bet size on the Betfair Exchange will be reduced from 2 (GBP) to 1 (GBP).