This is a calculator for the popular Betfair game "Card Derby Racing", one of Betfair's "Exchange Games" products. To use it, you input the cards that have been removed as handicap, and those played to move the horses, then click the "Submit" button. It then calculates the odds (the decimal odds, Betfair-style) on each horse. These odds are calculated precisely, and are, to the best of my knowledge, correct. However, no warranty is offered: we recommend that you test it before using it for real bets.