Free Tool · Betting Math

Kelly Criterion Calculator

Find the bankroll-optimal stake from your win probability and the odds, with fractional-Kelly options.

The calculatorLive · no signup
Kelly Fraction
Kelly Criterion
$25.00Recommended Stake
2.5%% of Bankroll
$100.00Full-Kelly Stake
+5.0%Edge
X / TwitterReddit
The Kelly growth curvef* = 10%
FULL KELLY 10%¼ KELLY 2.5%0.0%4.5%9.0%14%18%BET FRACTION OF BANKROLL →
▶ Open the bankroll simulator→
Frequently asked2 questions
Should I use full Kelly?
Full Kelly maximizes growth but is volatile. Many bettors use ½ or ¼ Kelly for much lower swings at nearly the same long-run growth.
What if the edge is negative?
Kelly returns zero, there is no bankroll fraction that grows your money on a losing bet.
More free toolsBetting calculators
Parlay Calculator→Combine multiple bets into one parlay and see the combined odds, total payout, and implied probability.Bet Calculator→Enter your odds and stake to see the exact payout, profit, and implied probability of a single bet.Odds Converter→Convert betting odds between American, decimal, and fractional formats, and see the implied probability.Expected Value Calculator→Estimate the expected value of a bet from your win probability and the offered odds.No-Vig Fair Odds Calculator→Remove the sportsbook's margin from a two-way market to get the fair odds and fair probability.Arbitrage Calculator→Check whether two prices form an arbitrage and get the stake split for a positive return on every outcome.

Beyond the math

Want the matchup context behind this number?

Ask Courtside→

Stop dashboard-hopping.
Ask a question.

Start askingJoin Discord

Join the Discord for pick notes, slate questions, product drops, and smarter NBA and MLB conversation.

Kelly Criterion Calculator - Optimal Bet Size | Courtside