Math & measurement
Edge
The percentage by which your expected return exceeds break-even on a bet — a 55% true probability at even money is a 10% edge. Real, durable edges in modern markets are small and usually come from price (line shopping, beating the close) rather than from out-predicting the market.
See these numbers on your own bets
Bankroll Guardian tracks every bet and computes your P&L, ROI, CLV, and where you win and leak — free to start, no card required.