Kelly Criterion Calculator
Quick Facts
- Computes optimal stake fraction (Kelly %).
- Inputs: bankroll, odds, win probability.
- Outputs: Kelly %, amount, half-Kelly, EV%.
How to use
Steps
Add bankroll, your price, and win probability. Read Kelly % and amount; consider half-Kelly for a conservative approach.
Formula & definitions
Formula: Kelly = (b·p − (1 − p)) / b, where b = (odds − 1)
- Kelly Fraction
- Stake % that maximises long-term growth.
- Half-Kelly
- Conservative variant to reduce variance.
Kelly Criterion Calculator
| Kelly % | Kelly Bet | ½ Kelly Bet | Expected Value % |
|---|---|---|---|
0.00% | 0.00 | 0.00 | 0.00% |
What is the Kelly Criterion? [Optimal Staking]
The Kelly Criterion is a bankroll management formula that suggests how much to stake for long-term growth while managing risk. It is widely used by professional bettors and analysts worldwide.
How Does Kelly Work?
- Enter your bankroll, the odds (any format), and your estimated probability of winning.
- The calculator outputs the optimal bet size as a % of your bankroll (Kelly %) and in cash units.
- Kelly stakes aim to improve long-term growth but can be aggressive—many experts use a fractional Kelly (e.g., half Kelly) for more conservative risk management.
- Expected value (EV) is shown, so you can quickly see if your edge is positive.
Why Use Kelly? [Benefits & Strategy]
- Always stake in line with your real edge—never overbet or underbet.
- Helps avoid blowing your bankroll on variance or short-term swings.
- Simple, quick, and perfect for high-frequency betting or investing.
- Backtested and used by world-class sports bettors and financial pros.
Updated 03 Apr 2026 SAST
Why it matters
Use the Kelly Criterion Calculator to sanity-check prices, remove guesswork, and make faster decisions when odds move.
Example
Example: Odds 2.00, win probability 55%. Full Kelly suggests staking 10% of bankroll.
Who it's for
Designed for bankroll sizing when placing sports betting bets in South Africa.
Use cases
- Plan stake sizing across sports betting sites and online sportsbooks.
- Manage bankroll risk on sports betting apps using fractional Kelly.
Practical tips
- Verify the odds are still live before relying on the output.
- Treat the results as guidance, not a guarantee.
- Compare multiple sportsbooks to validate value.
FAQs
What’s fractional Kelly?
Using a fraction of full Kelly, e.g., 50%.
Does Kelly guarantee profit?
No—variance still applies; it’s a sizing method.
Can I use any odds format?
Yes—tool converts odds internally.
Is Kelly good for sports betting?
It is a sizing method that helps manage risk.