Every bookmaker price has a margin baked in. Enter the odds for all outcomes of a market and this calculator strips that margin out, showing the fair probability and fair odds for each outcome, plus exactly how much the book is charging you.
Enter decimal odds. Fill two fields for a two-way market (over/under, BTTS) or all three for 1X2. Leave the third blank for two-way markets.
Convert every price in a market to implied probability (1 divided by decimal odds) and add them up. The total is never 100%. A 1X2 market priced 2.05 / 3.60 / 3.90 implies 48.8% + 27.8% + 25.6% = 102.2%. That extra 2.2% is the vig, also called the overround or margin: the bookmaker's built-in fee on the market.
The vig hides the bookmaker's real opinion. The fair probabilities are what remains after you scale the implied numbers back down so they sum to exactly 100%. Those fair numbers are the correct benchmark for every value calculation you will ever do.
Step 1: implied probability of each outcome = 1 / decimal odds.
Step 2: market total = sum of all implied probabilities. Margin = total − 100%.
Step 3: fair probability = implied probability / market total.
Step 4: fair odds = 1 / fair probability.
This is the standard multiplicative method: it distributes the margin across outcomes in proportion to their probability. Sharp bettors sometimes prefer weighting more of the margin onto longshots (because bookmakers do exactly that, a pattern called the favourite-longshot bias), which means true fair odds on favourites are often even slightly better than this calculator shows. As a first pass, the proportional method is the accepted standard.
Compare bookmakers honestly. A 4.5% margin book offering 2.10 can be worse than a 2% margin book offering 2.08 on a different line. Margin, not headline price, is what you pay over hundreds of bets.
Benchmark your own model. If your Poisson estimate says 55% and the no-vig market says 50%, you have a 5-point disagreement with the sharpest opinion available. That gap, not the raw odds, is your edge estimate. Feed it to the Kelly calculator to size the stake.
Track closing line value. Comparing the no-vig closing price against the price you took is the fastest reliable way to know whether you are betting well. Our CLV guide covers the full method.
Typical margins to expect: 2 to 3% on top-league 1X2 at sharp books, 4 to 7% at recreational books, and 8%+ on niche leagues and player props. The margin on our own graded picks is visible in every entry on the track record, because we record the odds at posting time.
What does a no-vig calculator do?
It converts each price in a market to implied probability, measures how far the total exceeds 100% (the bookmaker margin), and rescales every probability so the market sums to 100%. The result is the fair probability and fair odds for each outcome.
What is a normal bookmaker margin?
Sharp bookmakers run 2 to 3% on major football match odds. Mainstream books typically run 4 to 7%. Niche competitions, cups and player markets often carry 8% or more.
Are no-vig odds the true probability?
They are the market's best estimate with the fee removed, which is the best free benchmark that exists. They are not gospel: the market can be wrong, especially in smaller leagues, which is where a model edge is most likely to survive.
Why do my three outcomes add to more than 100%?
That is the point: the excess over 100% is exactly what the bookmaker charges. Odds of 2.05, 3.60 and 3.90 sum to 102.2% implied, meaning a 2.2% margin.
Does removing the vig equally across outcomes have a flaw?
Yes, a small one. Bookmakers load more margin onto longshots than favourites, so proportional devigging slightly overstates fair odds on longshots and understates them on favourites. For most uses the difference is under half a percentage point.
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