1. Odds Converter
Convert between formats and see the implied probability instantly.
2. Kelly Criterion Calculator
The Professional Guide to Kelly Criterion & Odds
If you want to move from a casual bettor to a profitable one, understanding bankroll management is more important than picking winners. The Kelly Criterion is the gold standard for sizing bets in sports betting, stock trading, and advantage play.
1. Finding “Value” with the Odds Converter
A “Value Bet” occurs when the probability of an outcome is higher than the probability suggested by the bookmaker’s odds. Use our converter to find the market’s expectation:
- Decimal Odds: Divide 1 by the odds (e.g., $1 / 2.00 = 0.50$ or 50%).
- American Odds: For positives, $100 / (Odds + 100)$. For negatives, $Odds / (Odds + 100)$.
If your research suggests a team has a 60% chance to win, but the odds converter shows an implied probability of 52%, you have a 8% edge.
2. Kelly Strategy Comparison
| Method | Risk Level | Best For |
|---|---|---|
| Full Kelly | High | Maximum growth, high volatility. |
| Half Kelly | Moderate | Professional standard balance. |
| Quarter Kelly | Low | Long-term safety & beginners. |
3. The Math Behind the Magic
The formula $f^* = (bp – q) / b$ ensures that you never go broke while betting. Because the stake is a percentage of your current bankroll, your bet sizes decrease during a losing streak and increase during a winning streak, providing a built-in “compounding” effect.
Frequently Asked Questions
Yes, but the win probability drops significantly, and the odds (b) increase. The formula remains the same, but the recommended stake will usually be much smaller.
This means the bookmaker’s margin (the “vig”) has eaten your edge, or the odds are too low for your estimated win chance. In this scenario, the mathematically correct bet is $0.
