Kelly Criterion Calculator 2025
The Kelly Criterion calculator helps sports bettors determine optimal bet sizes based on their edge and bankroll. Whether you're new to sports betting or an experienced bettor, this free tool applies the Kelly Criterion formula to maximize your potential returns while managing risk.
What is the Kelly Criterion?
The Kelly Criterion is a mathematical formula used in sports betting and investing to calculate the optimal bet size for maximizing long-term growth while minimizing the risk of bankruptcy.
Why Use Kelly Criterion?
Professional sports bettors use the Kelly Criterion to: • Optimize bankroll growth • Protect against losses • Make mathematically sound betting decisions
Kelly Criterion Calculator
Your estimated edge on each bet
Adjust what percentage of the optimal Kelly bet size to use
30% of optimal size
Strategy Summary
With a 5.0% edge and 30% Kelly fraction, you should bet 1.6% of your bankroll per bet. This conservative approach is expected to grow your bankroll by 0.1% per bet on average, with a maximum drawdown risk of 4.0%.
Understanding the Kelly Criterion
The Formula
The Kelly Criterion uses your edge and odds to calculate optimal bet size.
Kelly % = Edge / Odds
Where edge is your expected value
Fractional Kelly
Most professionals use a fraction of the full Kelly recommendation.
Common fractions:
25% to 50% of full Kelly
Risk Management
Balance growth potential with bankroll protection.
Key factors:
Edge accuracy, risk tolerance
Important Note
The Kelly Criterion assumes you can accurately estimate your edge. Always be conservative with your estimates and consider using a fractional Kelly approach to reduce risk.
Frequently Asked Questions
What is the Kelly Criterion in sports betting?
The Kelly Criterion is a mathematical formula used in sports betting to calculate the optimal bet size based on your edge and probability of winning. Professional bettors use this formula to determine what percentage of their bankroll to risk on each bet, maximizing long-term growth while minimizing the risk of losses.
What is the Kelly Criterion formula?
The Kelly Criterion formula is: Kelly % = (bp - q) / b, where 'b' is the decimal odds minus 1, 'p' is your probability of winning, and 'q' is your probability of losing (1 - p). For example, if you have 60% chance of winning at decimal odds of 2.0, the Kelly formula recommends betting 20% of your bankroll.
How do I use the Kelly Criterion calculator?
Enter your expected value (edge) and adjust the Kelly fraction slider to see different betting strategies. The calculator shows optimal bet sizes, projected bankroll growth, and risk metrics. Most professional bettors use between 20-50% of the full Kelly recommendation to reduce volatility.
What is a good Kelly fraction to use?
Most professional bettors use a fractional Kelly approach, typically between 0.25 (25%) and 0.5 (50%) of the full Kelly recommendation. This reduces volatility while maintaining most of the growth benefits. Using more than 60% of the full Kelly size is generally considered aggressive and risky.
Why does the calculator warn about high expected values?
Expected values above 20% are extremely rare in real betting markets. If you're calculating such high edges, it's important to double-check your probability estimates and calculations. Most successful value bets have edges between 2% and 10%.
How accurate is the Kelly Criterion calculator?
The calculator's mathematical formulas are 100% accurate, but the results depend on the accuracy of your edge (expected value) estimates. Success requires combining the calculator with good handicapping and realistic assessment of your betting advantage.