Kelly Criterion Calculator for Football Odds & Prediction Markets

Direct answer

The Kelly Criterion estimates a theoretical stake fraction from a model probability and available odds. Fractional Kelly is commonly used to reduce volatility. This calculator is educational only.

Informational and educational only — not betting, financial, legal, or investment advice. 18+; follow local laws.

Model probability (%)Odds formatAvailable oddsEducational example bankroll

Implied probability

47.62%

Model-market difference

7.38%

Full Kelly

14.09% · 14.09

Half / quarter Kelly

7.05% / 3.52%

Outputs are educational examples only. Kelly sizing can be volatile and is not a recommendation to place a bet or risk money.

Formula and example

For decimal odds O, let b = O − 1, p be the model probability, and q = 1 − p. The full fraction is f = (bp − q) / b. A non-positive result is shown as zero.

Example: a 55% probability at decimal odds 2.10 produces a positive mathematical result. It is still only as reliable as the underlying probability and price, neither of which guarantees an outcome.

Common mistakes and limits

Treating a model probability as certainty.
Ignoring commissions, limits, liquidity, and price movement.
Using a bankroll amount that is not genuinely affordable to lose.
Assuming a positive historical calculation means a future result is guaranteed.

FAQ

What does the Kelly Criterion calculate?

It estimates a theoretical fraction of a bankroll from a probability estimate and decimal odds. It does not predict an outcome.

Why use fractional Kelly?

Using a fraction of the full calculation reduces volatility when probability estimates or prices are uncertain.

Is the calculator betting advice?

No. It is an educational calculator and does not provide betting, financial, legal, or investment advice.