Kelly Criterion Calculator
Enter bankroll, odds and your chance to see the Kelly stake and its fractions.
- Edge over the price
- 5.00 points
- Break-even win chance
- 40.00%
| Fraction | Of bankroll | Stake |
|---|---|---|
| Full Kelly | 8.33% | $83.33 |
| Half Kelly | 4.17% | $41.67 |
| Quarter Kelly | 2.08% | $20.83 |
Full Kelly maximizes long-run growth if your probability is exactly right; an overestimate makes it overbet, which is why many people stake a fraction.
Model lines and crowd picks for 30 games in the next day and a half, as of Nov 4, 5:45 PM ET. Bandwagon's model, not a sportsbook line. We do not take wagers.
Educational tool. Bandwagon does not take or place wagers. Results are arithmetic on the numbers you enter, not advice.
How the kelly Criterion Calculator works
The Kelly fraction is f* = (b × p − q) / b, where b is the net odds (decimal − 1), p the win probability and q = 1 − p. It is the share of the bankroll that maximizes the long-run growth rate of repeated independent bets.
If p is not above the price's break-even chance, f* is zero or negative and the formula says do not bet. Kelly never bets more than the edge supports.
Full Kelly assumes p is exactly right and is volatile even then, so many people stake a fraction: half Kelly gives up about a quarter of the growth for much less variance, and quarter Kelly is gentler still. Overestimating the edge makes full Kelly overbet, which is its main hazard.
Kelly Criterion Calculator example
You enter
- Bankroll
- $1000
- Odds
- +150
- Your win probability
- 45%
- Odds format
- American (−110)
You get
- Edge over the price
- 5.00 points
- Break-even win chance
- 40.00%
| Fraction | Of bankroll | Stake |
|---|---|---|
| Full Kelly | 8.33% | $83.33 |
| Half Kelly | 4.17% | $41.67 |
| Quarter Kelly | 2.08% | $20.83 |
On a 1,000 bankroll at +150 with a 45% win chance, b = 1.5 and f* = (1.5 × 0.45 − 0.55) / 1.5 = 8.33%: full Kelly is 83.33, half 41.67, quarter 20.83.
Kelly Criterion Calculator questions
What is the Kelly criterion?
A staking formula that picks the bet size maximizing the expected logarithm of your bankroll, for repeated bets with a known edge.
What is half Kelly?
Staking half the Kelly fraction. It gives up some growth for a much smoother ride, and it protects against an overestimated edge.
What if Kelly is negative?
The bet has no edge at your probability, so the calculator shows no bet.
Does Kelly work for parlays?
Treat the parlay as one bet with its combined odds and its combined probability. The probability is the weak part.
Related calculators
Expected Value Calculator
The average result of a bet if your win probability is right, and the edge over the price.
Bankroll and Unit Size Calculator
Set a unit as a share of your bankroll and see how many losses in a row it takes to hurt.
Implied Probability Calculator
The win chance a price implies, with the sportsbook's margin taken out.