Free tool
Enter a two-way market and see the fair odds and probability once the book's margin is removed — plus how much hold is baked in.
Both sides of a market include the book's margin (the vig or hold). Removing it reveals the probability the market is actually implying for each side — the consensus fair price hidden inside the posted odds.
A standard -110/-110 spread market holds about 4.5%. Anything above that on a two-way market is expensive; the calculator shows the exact hold percentage for any pair of prices you enter.
No — they're what the MARKET implies once its margin is removed, not our model's view and not a forecast. They're the honest baseline to compare any price against.
Book's hold (margin): 3.48%. That's the edge built into the two prices; the fair odds above are what the market implies once it's removed.
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The honest explainer
The two sides of a market imply probabilities that sum past 100% — the excess is the book's margin. Devigging rescales both sides back to 100%, revealing the probability split the prices actually encode once the margin is stripped.
That fair line is the market's opinion, cleaned up. It is useful as a benchmark — for grading a price at another book, valuing a promo, or checking a hedge — not as a crystal ball.
−150 / +130: implied 60.0% and 43.5%, summing to 103.5%. Divide each by 1.035 and the fair split is 58.0% / 42.0% — a fair price of about −138 / +138. If another book is offering +145 on the underdog, you now have a measured comparison instead of a hunch.