Calculate the optimal percentage of your bankroll to wager on any bet to maximize long-term growth while controlling risk.
Enter your bankroll, odds, and estimated true win probability to get optimal stake recommendations.
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The Kelly Criterion is a mathematical formula that determines the optimal fraction of your bankroll to wager on a bet, balancing aggressive growth with risk of ruin.
Formula: f* = (bp - q) / b
where:
• f* = fraction of bankroll to bet
• b = decimal odds - 1 (net odds)
• p = probability of winning
• q = 1 - p (probability of losing)
Full Kelly maximizes geometric growth but is volatile. Half Kelly (50% of full) is widely recommended for sports betting to reduce drawdowns while still capturing most of the edge.
Input your current bankroll, the sportsbook odds, and your best estimate of true win probability (often from no-vig fair odds or modeling). The calculator instantly shows recommended stakes for full, half, and quarter Kelly strategies.
Once you identify high-edge opportunities using tools like our Expected Value or Fair Odds calculators, apply proper sizing with Kelly. For multi-leg bets or combining several selections with different edges, our versatile Parlay Calculator provides precise payout modeling and risk assessment, helping you decide whether to run correlated wagers as singles (Kelly-sized) or as a parlay for higher potential reward.