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Kelly Criterion Stake Calculator

Work out kelly criterion stake instantly with clear inputs, formula shown and shareable results.

About Kelly Criterion Stake Calculator

The Kelly fraction is (p x b - (1 - p)) / b, where b is decimal odds minus one; a zero or negative result means the bet has no edge and should not be backed. Full Kelly maximises long-run growth but with brutal variance, which is why most professionals stake a half or quarter of the Kelly figure.

Formulas

Kelly fraction

f = (p x b - (1 - p)) / b, with b = decimal odds - 1

Edge

edge = p x decimal odds - 1

Worked example

With the default values below, Kelly Criterion Stake Calculator returns Kelly stake as a share of bankroll of 8.333%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Bankrollminimum 0.01
1,000
Decimal oddsminimum 1
2.5
Your estimated chance of winningaccepts 0.1–99.9 %
45 %

Results

Kelly stake as a share of bankroll
8.333%
Full Kelly stake
$83.33
Half Kelly stake
$41.67
Your edge over the price
12.500%

Step by step

  1. 1Values used
  2. 2Kelly fraction
  3. 3Edge
  4. 4Kelly stake as a share of bankroll= 8.333
  5. 5Full Kelly stake= 83.33
  6. 6Half Kelly stake= 41.67
  7. 7Your edge over the price= 12.500

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Kelly Criterion Stake figure worked out?

f = (p x b - (1 - p)) / b, with b = decimal odds - 1. The Kelly fraction is (p x b - (1 - p)) / b, where b is decimal odds minus one; a zero or negative result means the bet has no edge and should not be backed.

Why does this matter?

Full Kelly maximises long-run growth but with brutal variance, which is why most professionals stake a half or quarter of the Kelly figure.

What do I need to enter?

Enter bankroll, decimal odds, your estimated chance of winning. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

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