Skip to content
OddsRX
← All calculators

Value & stake

Kelly Criterion Calculator

Explore how your estimated edge and a fractional Kelly setting affect stake size.

Your inputs

Odds formats: −110, +150, 1.91 or 5/2.

Your result

How to read your result

Kelly sizes a stake from your estimated edge. Fractional Kelly scales that stake down. A small error in your probability estimate can substantially change the result.

At +120 with a 50% win probability, full Kelly is 8.33% of bankroll. Quarter Kelly on $1,000 gives a stake of about $20.83 before any optional cap.

Formula and assumptions

Full Kelly fraction f = (b × p − (1 − p)) ÷ b, where b = decimal odds − 1. Stake = bankroll × max(0, f) × selected Kelly fraction. The optional cap limits the stake further. This model considers one bet in isolation and does not account for correlated positions or estimation error. Zero or negative edge produces a zero stake.

Expected valueCompare your win-probability estimate with the offered price to calculate expected profit.No-vig oddsRemove the market overround from a two-outcome price and compare fair probabilities.Hedge a positionCalculate the opposite-side stake that aims to equalize the two net outcomes.