Model │ Math · Free tool
Expected Value
A bet is only worth making if your read on the outcome beats the price on offer. Put your probability against the odds and a stake. The gap shows up in dollars and as an edge.
A percentage above 0 and below 100.
A price in any format, +120, 1.91 or 10/11.
A dollar amount greater than zero.
Your probability is the honest part, the price is just arithmetic.
, Expected value ,
- Return on stake ,
- Your edge ,
- Break-even win % ,
- Fair odds at your % ,
Is the bet worth making?
Expected value is the average result of a bet placed endless times. Positive, the bet makes money long-term. Negative, it bleeds, however the ticket lands.
- Break-even win %
- The implied probability of the offered price, how often the bet must win just to come out flat. Beat it with your real win rate and the bet is worth making.
- Your edge
- Your probability minus the break-even probability. A positive edge is the whole game; a negative one means the price has you beaten before the event starts.
- Expected value
- The edge turned into money, your average profit or loss per bet at this stake. Return on stake is the same figure as a percentage, for comparing bets of different sizes.
The math is honest. The input is not. A win probability is an estimate, and an optimistic one quietly turns a losing bet into a winning-looking number. Be ruthless with that figure.