KELLY CRITERION CALCULATOR
Free · no signup · runs entirely in your browser
Kelly sizes a bet by your edge. Enter the price and your honest estimate of the true win probability. If you have no edge, Kelly tells you to bet nothing, which is the most useful thing it does.
The maths: f* = (b x p - q) / b, where b = decimal odds - 1, p = your win probability, q = 1 - p. Stake = f* x bankroll. Most bettors use half or quarter Kelly because p is an estimate, not a fact.
FAQ
What is the Kelly criterion?
A formula for bet sizing that stakes in proportion to your edge, maximising long-run bankroll growth. With no edge it returns zero.
Why use half Kelly?
Full Kelly assumes your win probability is exactly right. It almost never is, and overestimating your edge causes severe drawdowns, so fractional Kelly is standard.
What if Kelly gives a negative number?
It means the price is worse than your estimated probability justifies. The correct stake is zero, not a small bet.
Built by CAPTRACKER, which tracks public handicappers and settles every pick automatically against the final score. If you are about to follow someone's picks, look up their record first.