Free calculator
No-vig calculator
Enter both sides of a market. You will see the fair odds with the margin removed, and how much vig the sportsbook built into the price.
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Enter the prices on each side.
Fair odds here use the proportional method, which splits the margin across the sides in line with their prices. It is the standard approach and the one most models start from.
Fair odds tell you what a book really thinks
Once the margin is stripped out, differences between sportsbooks become obvious. BetSuite watches for the moments those differences get big enough to back both sides.
Download Free →What the vig is
Add up the implied probabilities on both sides of a market and you will get more than 100 percent. A standard -110 pair implies 52.38 percent each, or 104.76 percent together. That extra 4.76 percent is the sportsbook’s margin, known as the vig, the juice or the overround.
It is the reason betting both sides at one book always loses money, and the reason a price is never a straight statement of probability.
What no-vig odds are for
Stripping the margin out leaves what the book actually thinks, expressed as a clean probability that sums to 100 percent. That number is useful in three ways: comparing books on a level footing, judging whether a price elsewhere is generous, and feeding a probability estimate into a sizing formula like Kelly.
Sharp books are the useful ones here. A no-vig price from a book that prices tightly is a reasonable proxy for the true chance, which is why it is often used as the benchmark to measure other books against.
How the margin is removed
This calculator uses the proportional method: divide each side’s implied probability by the total. Two sides at 52.38 percent each divide by 104.76 to give a clean 50 percent apiece, or +100 on both.
Other methods exist, and they disagree most on lopsided markets where one side is a heavy favourite, because margin is not always spread evenly across a market. For everyday two-way lines the proportional method is the standard starting point.
When two different books disagree enough that their raw prices total under 100 percent, you are looking at an arbitrage rather than a margin. The arbitrage calculator handles that, and our guide to vig covers the concept in more depth.