No vig calculator
Remove the book's margin from a two way or multi way market and read the fair probability of each outcome.
Leave blank for a two way market.
Leave blank for a two way market.
Fair probabilities
This is the proportional method, which spreads the margin across outcomes in proportion to their posted probability. Other methods exist and they disagree most on lopsided markets, where one side is a heavy favourite.
How it is calculatedOpenClose
Convert every posted price to an implied probability and add them up. The sum above 1 is the book's margin, also called the overround. Each fair probability is that outcome's implied probability divided by the sum, so the fair probabilities add to exactly 1.
- The proportional method spreads the margin across outcomes in proportion to their posted probability. Other methods exist and disagree most on lopsided markets.
- The overround is the book's margin across the whole market, not the reader's expected loss on any one side.
- Fair probabilities are an estimate of what the market believes. They are not a prediction and they are not our model.
Worked example, illustrative
Both sides at -110
- 1Each side implies 52.38%, so the two add to 104.76%.
- 2The book's margin is 4.76%.
- 3Each fair probability is 50.00%, while each side still needs 52.38% to break even at the posted price.
These figures are an illustration of the formula, not a claim about any real market.
Related guidance
Research only. This tool does arithmetic on numbers you type. It does not place bets, submit entries, estimate a probability for you, or tell you what to risk. If gambling stops being fun, call 1-800-GAMBLER.