Kelly Calculator
Back to the calculator.
Quick Kelly calculator
Accepted as % (e.g. 60,2) or 0–1 (e.g. 0,602).
If filled, p = 1 / fair odds. Typing here clears “Fair probability”.
EV%
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Kelly fraction f*
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Recommended stake (€)
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Parsed p / fair odds
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What is the Kelly Criterion?
The Kelly fraction maximizes the long-run growth of your bankroll when you have an edge. For decimal odds o with fair win probability p and b = o − 1, the optimal fraction is:
f* = (b·p − (1 − p)) / b
- Cap at 0 if negative; many scale with a divisor (e.g. half-Kelly → divisor 2).
- Recommended stake =
bankroll × f* / divisor, then round to your step.
Odds formats & conversions
Use the Odds format selector to switch between Decimal, American and Fractional inputs. See Odds formats for quick conversions, or derive no-vig probabilities with the Hold/Overround tool.
Example
If p = 0.6020 and the softbook offers o = 1.72, then b = 0.72 and f* = (0.72×0.6020 − 0.3980)/0.72 ≈ 0.0248 ⇒ stake 2.48% of bankroll (before divisor).
Notes
- Kelly is volatile; many use quarter- or half-Kelly to manage drawdowns (see Max drawdown).
- Never exceed full Kelly; if
f*is negative, the edge is not positive.
Need the big EV/Kelly tool? → FairOdds calculator.