No-Vig Fair Odds Calculator
Bookmakers price every market above 100% so they make money whatever happens. Removing that margin leaves the fair odds — the market's honest view of the event, and the number worth comparing every other price against.
Calculator
How to use the no-vig fair odds calculator
Enter the price on each outcome of the same market at the same bookmaker. The calculator shows the margin being charged and the fair price on each side once it's removed.
Use a sharp book's market as the input. Fair odds derived from a soft book just tell you what that book thinks, whereas the no-vig line from a sharp market is the closest thing to a consensus true price — and any book offering longer than it is offering value.
The formula
Convert every outcome to its implied probability, add them up, then divide each one by that total:
fair probability = (1 ÷ odds) ÷ Σ(1 ÷ odds)
The fair price is one divided by that probability. The sum before scaling is the market percentage — subtract 100% and you have the margin.
This is the proportional method, the one most calculators use. It spreads the margin evenly across outcomes, which is a simplification on lopsided markets where books load more of it onto the longshot.
A worked example
A head-to-head is priced $1.90 each side. That's 52.63% + 52.63% = 105.26%, so the book is charging a 5.26% margin.
Scaling both to add to 100% gives 50% each, so the fair price on each side is $2.00. If another book has one of those sides at $2.10, you're being offered better than fair.
