To use this page you only need two things: a bookmaker to take your bet, and an online exchange where you can place lay bets on the same game or event. Betfair Calculator. Easily calculate your back and lay odds on betting exchange sites such as Betfair, Betdaq and WBX. Betting on betting exchange websites. If you've had a bet and it's shortened in price, use this calculator to see how you can guarantee yourself a profit using the betting exchanges - win or lose. Gambling can be addictive. From this example above, it is easy to work out the formula to convert lay odds into effective back odds, i. Alternatively, you can click the pink boxes at the Exchange and lay Liverpool at odds of 2. Catering to all experience levels our aim is simply to empower bettors to become more knowledgeable. Original Wager Details Wager type: A hedging opportunity to lock in a profit arises when you have made a wager and the statistik champions league have since shifted in your favour.