Calculators / Kelly calculator
Kelly calculator
How much of your bankroll to bet when you have an edge.
Enter the odds, your win probability and your bankroll.
How it works
Full Kelly bets edge divided by net odds: (win probability x decimal odds - 1) / (decimal odds - 1). It grows a bankroll fastest in theory, but swings hard and assumes your win probability is exact.
Most +EV bettors stake a quarter of that. Quarter Kelly gives up a little growth for far smaller drawdowns, and it forgives an estimate that is slightly off.
With no edge (the price is worse than fair), Kelly says bet nothing.