Min/max odds when betting in-play
There are two important features of in-play betting on Betfair: high price volatility and 1 second delay between moments when your bet is placed and when it gets matched. Together they may cause some bets to match at odds outside min/max limits. It happens because when the bot “looks” at prices they might be within the limits and the bet is fired, but after 1 second of the artificial in-play delay prices may jump or drop significantly and matched price will be outside the limits. You should consider this risk when betting in-play.
Small bets in-play
Small bets or bets with size below minimum £2 require more operations (and therefore more time) to fire than normal bets. When betting before the off it is not a problem, but when betting in-play and taking into account thoughts from the previous paragraph, this extra time required to place small bets may cause your bet unmatched or matched at worth odds. We advice to bet in-play only with normal stakes, above Betfair minimum of £2.
The bot always tries to get your bet matched at best available odds considering all betting conditions. If for some reason (e.g. price volatility) your bet is not matched, the bot will attempt to cancel and place it again.
Minimum potential profit
Currently Betfair requires at least 2p potential profit for each bet. This means that if you try to place small stake at small odds, you may get INVALID_PROFIT_RATIO error. For example, placing £0.10 at 1.10 will result in the above error because in this case potential profit is only £0.01 which is less than 2p. Therefore you should choose either higher stake or higher odds (e.g. £0.10 at 1.20 or £0.20 at 1.10).