Vig

Add the raw implied probabilities of both sides. If they sum to 105%, about five percentage points are margin. Books build that margin in different ways. The sum is not a hidden opinion about who wins.

Worked example, not a price from this preview: both sides at 1.90. Each raw implied probability is about 52.6%. Together they sum to about 105.3%, so the overround is about 5.3% even though the fair split is 50% and 50%. Equal prices are not zero-margin prices.

To remove the vig, divide each raw probability by the sum of the raw probabilities. Do that before you compare a price with anything else. This site does not show a model next to the price. The comparison column is a coming-soon placeholder.

• Raw implied = 1 ÷ decimal price.
• Overround = (raw A + raw B) − 1.
• Fair implied = raw ÷ (raw A + raw B).