Oddsator
All toolsOdds ConverterBet CalculatorParlay CalculatorMargin CalculatorValue Bet FinderKelly CriterionArbitrage CalculatorBest Odds ComparisonDropped Odds

Kelly Criterion

Calculate the mathematically optimal stake size to maximize bankroll growth.

Kelly fraction (conservative betting)
Enter your bankroll, your estimated win probability, and the decimal odds to see your recommended Kelly stake.

What is the Kelly Criterion?

The Kelly Criterion is a formula that tells you how much of your bankroll to stake on a single bet given your edge. It uses your estimated win probability and the decimal odds to work out the fraction that grows your bankroll fastest over the long run — staking more when your edge is bigger and less when it's thin. This calculator turns that fraction into a concrete stake in kronor, and lets you scale it down to half or quarter Kelly.

How to use the Kelly calculator

  1. 1
    Enter your bankrollType in the total amount you've set aside for betting, since Kelly sizes every stake as a share of that bankroll.
  2. 2
    Add your probability and the oddsEnter your own estimated win probability as a percentage and the decimal odds offered by the bookmaker.
  3. 3
    Pick a Kelly fractionChoose full, half, or quarter Kelly to read off the recommended stake and the edge it's based on.

Why use fractional Kelly?

Full Kelly is mathematically optimal for long-term growth, but it's punishingly volatile — a run of losses can wipe out a large chunk of your bankroll before things recover. Because real-world probability estimates are never perfect, overbetting a single mistake hurts more than underbetting, so most bettors use half or quarter Kelly to cut the swings. If the calculator shows a negative edge, the correct Kelly stake is zero: the bet isn't worth making.

A worked example

Say your bankroll is 10,000 kr, you rate a selection at 55% to win, and the decimal odds are 2.00. Your edge is (0.55 × 2.00) − 1 = 0.10, and full Kelly stakes that edge divided by the net odds of 1.00 — a 10% fraction, or 1,000 kr. Half Kelly would cut that to 500 kr and quarter Kelly to 250 kr, trading some growth for a much smoother ride.

Kelly Criterion FAQ