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Kelly Criterion / Staking Calculator

For readers examining sensitivity to an assumed probability. A positive model output can become negative when that assumption changes.

Examples are hypothetical. CU = currency units. Use one consistent currency wherever CU appears. No live prices or provider data are fetched.

How to read the result

The model treats the probability you entered as correct and assumes a binary win or loss. It does not estimate that probability, establish a safe stake or account for correlated bets, uncertainty, fees or bankroll needs.

Formula

Set p = estimated probability / 100 and b = decimal odds − 1.
Raw Kelly fraction f = (bp − (1−p))/b. Retain the signed value; modelled fraction = max(0,f) × selected fraction.
Modelled amount = bankroll × modelled fraction. EV of entered stake = stake × (p × odds − 1).

Worked example

Odds 2.20, p = 0.50: raw f = (1.20×0.50−0.50)/1.20 = 8.3333%. Half Kelly = 4.1667%; 1,000 CU × 4.1667% = 41.67 CU. EV of 10 CU = 1.00 CU.

Worked examples

Read the detailed guide: Kelly and expected value: what a probability assumption changes

Input specification and SEO alternatives

Input	Type	Units	Default	Limits / choices
Decimal odds	Multiple input	None	`2.2`	1.000001–1000000
Your estimated win probability	number	%	`50`	0.000001–99.999999
Illustrative bankroll	number	CU	`1000`	0.01–100000000
Stake for EV calculation	number	CU	`10`	0–1000000
Kelly fraction	Choice	None	`0.5`	Full; Half; Quarter

Meta description

Explore the Kelly formula and expected value using your own probability estimate. Modelled amounts are not staking recommendations.

SEO title alternatives

Kelly Criterion Calculator: Modelled Stakes
Kelly Fraction and Expected Value Calculator
Explore Kelly Staking Assumptions

Outputs use English number formatting. Monetary amounts use two decimals; asset quantities use up to eight. Calculations retain unrounded intermediate values except the cent allocation stated for arbitrage.