All
Value & Bankroll

Kelly Criterion Calculator

The Kelly Criterion is a theoretical sizing model. Its output is only as reliable as the probability estimate entered, so many users review fractional Kelly results as a more conservative reference.

Inputs

Live
%
$

Enter 0.5 or 50 for half Kelly. Values above 100% are not accepted.

Sizing results

Live

50% Kelly position

$27.50

Fractional Kelly2.75%
Full Kelly5.50%
Full Kelly amount$55.00
Estimated edge5.00%
Market-implied probability52.38%

Method and assumptions

How to use this calculator

The Kelly Criterion estimates a theoretical bankroll fraction from your probability estimate and the offered price.

Formula

Kelly fraction = (b × p − q) ÷ b, where b is net decimal odds, p is win probability, and q is loss probability.

Why fractional Kelly matters

Probability estimates are uncertain. Half or quarter Kelly scales the theoretical result down, but no fraction removes the risk of loss or a bad probability estimate.

Keep checking the math

Related calculators

View the full library →

Value & Bankroll

Expected Value Calculator

Compare your probability estimate with the available price and calculate estimated expected value.

Open

Market Pricing

Implied Probability Calculator

Convert American, decimal, or fractional odds into implied probability—or convert a probability back into equivalent odds.

Open

Payout & Risk

Hedge Calculator

Estimate an opposing stake and compare the projected result under either outcome.

Open

Calculator results are informational estimates based on the values entered. They do not guarantee an outcome. Confirm current prices, rules, fees, liquidity, limits, and eligibility on the relevant platform.