Parlay Killer is a math tool only — not betting advice. You must be 18+ to use this service.
PARLAYKILLER
The math the sportsbook doesn't want you to see
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Parlay Builder0 Legs
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Parlay Killer
How is this calculated?
Every odds line implies a probability. We convert each leg's odds to a true probability, strip out the 4.5% sportsbook hold, then multiply all legs together. A 3-leg parlay with true probabilities of 55%, 48%, and 51% has a combined win chance of 13.4%. The lower the number, the more the sportsbook is counting on you not to do this math.
HOW WE GOT HERE — Show the Math
True Win Probability
?This is the real probability of your parlay hitting, calculated from market odds with the sportsbook's built-in profit margin (the 'vig') stripped out. It is not a prediction — it reflects what the market implies.
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After 4.5% Book Hold Applied
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Expected Value ?EV tells you how much you win or lose on average per bet over time. Negative EV means the house has an edge. Positive EV means the odds are in your favor — rare for parlays.
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Potential Payout ?What the sportsbook pays if you win. 'Fair value' below it is what you'd be paid if there were zero house edge.
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Compounded hold
Book Edge
Warnings
Leg Breakdown
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Description
Odds
Book Implied
True Prob
Better Bet
Lower-Edge Alternative
Value Finder — Lowest-Juice Lines Today
EV is calculated by comparing each side's book-implied probability against the no-vig (fair) probability derived from the DraftKings two-way market. Lines closest to 0 EV have the least juice. DraftKings lines only. Not a guarantee of profit.