The Kelly Criterion is the gold standard for bankroll management in sports betting. It tells you exactly how much to bet to maximize wealth growth based on your edge. But standard Kelly calculators have a major flaw: they only work for single bets.
When you bet on a Parlay (Accumulator), the math changes. You aren’t just calculating one edge; you are compounding probabilities across multiple events. Our Kelly Criterion for Parlays Calculator does the heavy lifting. It combines the true probabilities of every leg in your bet to determine the exact “Global Edge,” and then recommends the mathematically optimal stake size to protect your bankroll from the high variance of multi-leg betting.
Parlay Kelly Calculator
Bankroll ManagementHow to Use the Calculator
Using the Kelly Criterion for parlays requires discipline. You cannot simply input the bookmaker’s odds; you must know the true probability of winning. Here is the workflow:
- Setup Your Bankroll: Enter your current total bankroll.
- Select Kelly Fraction (Crucial):
- Parlays have massive variance. We strongly recommend using the slider to select 0.25x (Quarter Kelly) or 0.5x (Half Kelly). Betting “Full Kelly” on parlays is often too volatile for most bettors.
- Add Your Legs:
- Bookie Odds: The price the sportsbook is offering (e.g., 1.90).
- Fair Win %: Your estimated probability of that specific leg winning (e.g., 55%).
- Review the Edge: The calculator multiplies the probabilities to find the “True Win Probability” of the entire parlay. If the total edge is positive, it suggests a dollar amount to bet.
Real-World Examples: Sizing Your Risk
Why is a specialized calculator necessary? Because small edges—and small mistakes—compound exponentially in parlays.
Example 1: The “Value” Double
You identify two football games where you believe the teams are favorites.
- Leg 1: Odds 2.00, You believe true chance is 55%.
- Leg 2: Odds 2.00, You believe true chance is 53%.
- The Math: The Bookie offers total odds of 4.00. Your combined true probability is 29.1%.
- The Kelly Recommendation: Even though both legs are +EV individually, the combined risk is high. A Half-Kelly calculation might suggest betting only 2-3% of your bankroll, whereas a gut feeling might have led you to bet 5% or 10%.
Example 2: The Negative Edge Trap
You want to bet a 3-leg “Fun Parlay” on favorites.
- The Scenario: You estimate each team has a 60% chance to win. The bookie offers odds of 1.50 (-200) on each.
- The Calculation: 1.50 implies a 66% break-even point. Since your true probability (60%) is lower than the implied probability (66%), the specific leg has negative value.
- The Result: The calculator will flash “Do Not Bet” (Negative Edge). No matter how “safe” a parlay feels, you should never bet it if the math shows negative Expected Value.
Frequently Asked Questions (FAQ)
Why should I use Fractional Kelly (e.g., 0.5x) for Parlays?
Full Kelly assumes you know the exact probability of winning. In sports betting, our probabilities are just estimates. Since parlays have higher variance (longer losing streaks) and compounding estimation errors, using Fractional Kelly (betting half or a quarter of the recommendation) acts as a safety net to prevent draining your bankroll during a bad run.
Can I use this for “Same Game Parlays” (SGPs)?
No. This calculator assumes that each leg is an independent event (e.g., two different matches). In an SGP, outcomes are correlated (e.g., “Team A to Win” and “Team A QB to throw 2 TDs”). The math for correlated probabilities is much more complex and this tool will over-estimate or under-estimate the true odds.
What is “Fair Win %” and where do I get it?
Fair Win % is the actual mathematical probability of an event happening. You can derive this from your own handicap models, or by using “No-Vig” odds from sharp bookmakers (like Pinnacle). You cannot use the bookmaker’s standard implied probability, as that includes their profit margin.