Betting calculators
Free, no signup, and nothing is sent anywhere — the arithmetic runs in your browser.
Expected value calculator
Enter a price, what you think the real chance is, and your stake. Expected value is what a bet returns on average if you could make it many times — positive when your probability is higher than the price implies, and that gap is the only reason to take a bet.
Odds converter
Enter a price in any format and get the others, plus the probability it implies. American is standard in the United States, decimal across Europe and Australia, fractional in British racing — the same price written three ways.
Arbitrage calculator
Enter the best price available on each outcome and a total stake. Legs can be a bookmaker back, an exchange back or lay with commission, or a YES or NO contract on a prediction market — each is converted to the price of an equivalent back bet, so they can be combined freely. The calculator splits the stake so that every outcome returns the same amount, and tells you whether that return beats what you put in.