Vig (Juice) Calculator

How it is calculated

Each side's American moneyline is turned into an implied probability: for positive odds p = 100 ÷ (odds + 100), for negative odds p = |odds| ÷ (|odds| + 100). Then:

total = pA + pB
vig = total − 1
hold = vig ÷ total
fair A = pA ÷ total, fair B = pB ÷ total

The vig is the overround (how far the two probabilities exceed 100%); the hold is that excess as a share of the total, which is the book's margin on money wagered evenly on both sides. The fair percentages are the two sides rescaled to add up to exactly 100%. American odds are never between −100 and +100, so a value such as 50 or −50 in either field shows no result. Only two-way markets are handled, and the tool gives probabilities only, not converted odds.

Common mistakes

• Mixing up vig and hold. Vig is measured against 100% (here 4.76%), hold against the total of the probabilities (here 4.55%), so quoting one as the other overstates or understates the margin.
• Entering decimal odds such as 1.91 or fractional odds such as 10/11. Only American moneylines (−110, +150) are read here, and 1.91 is below 100 in size, so it shows no result.
• Dropping the minus sign. Entering 110 instead of −110 on a favourite turns it into a +110 underdog, and the vig and fair probabilities come out completely different.
• Using a market with three outcomes (soccer 1X2, for instance) and feeding in two of them. The vig of a full three-way market needs all three probabilities, so a two-sided figure will be wrong.
• Treating the fair probability as a guaranteed true chance. It only strips the margin proportionally from the two prices; it says nothing about which side is actually mispriced.