Free tool
Enter your legs and the book's SGP price. We show the independent fair price and the correlation tax — how much the book shaves for pricing the legs together. Pure math, no signup.
Because the legs are correlated — when your quarterback throws for 300 yards, his receiver probably also went over — and the book prices that in. This calculator shows the gap between the independent fair price and what you're being offered: the correlation-plus-margin tax.
No — and the calculator says so on the page. Multiplying the legs assumes they're uncorrelated, which same-game legs never are. The gap it shows is an estimate of what the book charges for correlation and margin together, not a measure of value.
SGPs are among the highest-hold products a sportsbook sells; the calculator exists so you can see the tax before you pay it. That's information, not encouragement — bet responsibly, 21+.
“Independent fair” multiplies the legs as if they were uncorrelated. Same-game legs usually aren't, so this is not the true fair price — the gap is how the book is pricing correlation + its margin. Here the SGP pays less than independent (the usual correlation tax + vig). An estimate, not an edge. Bet responsibly · 21+
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The honest explainer
Legs from the same game move together — a QB's passing yards and his receiver's catches are one story told twice. Multiplying their individual prices as if independent produces a benchmark, and the gap between that benchmark and the book's SGP quote is the correlation tax you're being charged.
This calculator reveals the tax. What it cannot do is compute the true joint probability — nobody outside the book's pricing model knows that number.
Two −110 legs priced independently: 1.909² = 3.65, about +265. The book quotes the same-game combo at +180 (2.80). The 3.65 → 2.80 gap is the tax: you're paying for the correlation you're trying to exploit. Positively correlated legs are genuinely worth more than the independent price — the question the quote answers is how much of that worth the book kept.