No-Vig Fair Odds Calculator

What Is the Vig (Bookmaker Margin)?

The vig, short for vigorish and also called the overround or bookmaker margin, is the profit built into every bookmaker’s prices. It means that over enough bets, the bookmaker makes money whatever the results. It is also why the implied probabilities of every outcome in a market always add up to more than 100%.

In a perfectly fair market, such as a coin toss, each side would be priced at 2.00 (evens) and the implied probabilities would add up to exactly 100%. A bookmaker might offer 1.91 on each side instead: 52.36% each, 104.71% in total. The extra 4.71% is the margin. The no-vig calculator removes it and turns the bookmaker’s prices back into fair odds, 2.00 on each side in this case.

How to calculate fair (no-vig) odds

There are three steps:

• Add up the implied probabilities: for each outcome, work out 1 ÷ decimal odds, then add them together. A market with a 5% margin adds up to 1.05.
• Normalise: divide each outcome’s implied probability by that total. This is the fair probability with the margin removed.
• Convert back to odds: 1 ÷ each fair probability gives the fair decimal odds.

For a football match priced home 1.80 (55.56%), draw 3.50 (28.57%) and away 4.50 (22.22%), the total is 106.35%, a 6.35% margin. Dividing through gives fair probabilities of 52.24%, 26.87% and 20.90%, or fair odds of 1.91, 3.72 and 4.79. These are the default prices in the calculator above.

If the prices you enter add up to less than 100%, they cannot all come from one bookmaker’s market: you have found an arbitrage across bookmakers. Our arbitrage calculator works out the stakes.

Why does this matter for UK bettors?

Knowing the margin on a market tells you where to bet and whether a price is fair value. Margins on major UK football markets typically sit somewhere around 3% to 8%, depending on the bookmaker and the match. Betting exchanges charge commission on winnings instead, typically 2% to 5%, and their prices often sit closer to fair value than bookmakers’.

Comparing bookmaker margins

Bookmakers do not charge the same margin on every market. Smaller leagues and less popular sports often carry bigger margins than headline Premier League matches, and in-play markets usually carry more margin because the bookmaker is managing risk as the game moves. Use this calculator, or our betting margin calculator, to compare the same market at different bookmakers before you bet.

No-vig odds and value betting

Once you know the fair odds for a selection, compare them with the prices at other bookmakers. A bookmaker offering better than the fair odds is offering positive expected value on that selection, as long as the fair odds are a good estimate of the real chance. Our expected value calculator puts a number on that edge, and our bankroll management calculator sizes the stake with the Kelly Criterion.

No-vig odds and promotions

No-vig odds are a quick way to judge a price boost. A boosted price is only worth taking if it is meaningfully above the fair price. Use this calculator alongside our free bet calculator and matched betting calculator to judge the full value of an offer.