No-Vig Calculator: Remove the Margin and Find Fair Odds

Every price a bookmaker offers has a margin built in, also called the vig, juice or overround. The no-vig calculator below takes the prices for every outcome of a market, measures that margin and removes it, leaving the fair probability and fair odds of each outcome. It works on two-way markets such as a point spread or a tennis match and on three-way markets such as a football 1X2.

How to use the no-vig calculator

The tool needs the price of every outcome in one market, taken from the same bookmaker at the same moment. Mixing prices from different bookmakers measures something else and can even produce a negative margin.

• Enter the price of the first outcome in Outcome 1 and the second in Outcome 2. Fractions take a slash (5/6, 6/4), decimals take a point (1.91, 2.50) and American odds take a sign (-110, +130).
• Fill in Outcome 3 only for a three-way market, which in practice usually means the draw in a football (soccer) match result market. Leave it empty for anything with two outcomes.
• Read the bookmaker's margin first. It tells you how much the market charges in total.
• Then read the fair probability and fair odds of each outcome. Fair odds appear in decimal with the American equivalent in brackets, for example 2.00 (+100).

The default example shows -110 on both sides, the standard price on many US point spreads. The calculator returns a margin of 4.76% and, for each side, a fair probability of 50.00% and fair odds of 2.00 (+100). The formats can be mixed, so you can type one side as 10/11 and the other as -110 and get the same result, since both are the same price.

The formula: proportional margin removal

The calculator uses the proportional method, sometimes called the multiplicative method. It has three steps.

• Convert each price to an implied probability: 1 divided by the decimal odds. -110 is 1.909 in decimal, so its implied probability is 1 / 1.909 = 52.38%.
• Add the implied probabilities of all outcomes. The total is above 100%, and the part above 100% is the bookmaker's margin. For -110 and -110 that is 52.38% + 52.38% = 104.76%, a margin of 4.76%.
• Divide each implied probability by the total. 52.38 / 104.76 = 50.00%. The fair odds are 1 divided by the fair probability, so 1 / 0.50 = 2.00, which is +100 in American odds.

In short, fair probability = implied probability / sum of implied probabilities, and fair odds = 1 / fair probability. Because every outcome is divided by the same total, each one gives up margin in proportion to its own size. A favourite with a high implied probability loses more percentage points than an outsider does.

This is the simplest and most widely used way to remove the margin, but it is not the only one. Other methods, such as the power method and Shin's method, assume that bookmakers load more of their margin onto outsiders. They give slightly different fair numbers, and the gap is widest for long shots. None of them can tell you the true chance of an outcome. They only describe what the market is saying once the bookmaker's cut is taken out.

Worked examples: a moneyline and a football 1X2 market

Take an NFL moneyline with the favourite at -150 and the underdog at +130. In decimal those are 1.667 and 2.30. The implied probabilities are 1 / 1.667 = 60.00% and 1 / 2.30 = 43.48%, which add up to 103.48%. The margin is 3.48%, a little lower than on a -110 spread.

Divide each by 1.0348 and the fair probabilities are 57.98% for the favourite and 42.02% for the underdog. Their fair odds are 1.72 (-138) and 2.38 (+138). A fair two-way line always has mirror-image American prices like these, because without a margin the two sides balance exactly. So a $100 bet on the underdog at the market price of +130 wins $130, while the fair price would pay $138. The $8 difference is what the margin costs you on that side.

Now a Premier League match priced in decimal at 2.50 home, 3.20 draw and 3.00 away. The implied probabilities are:

• Home: 1 / 2.50 = 40.00%
• Draw: 1 / 3.20 = 31.25%
• Away: 1 / 3.00 = 33.33%

The total is 104.58%, so the margin is 4.58%. Dividing each figure by 1.0458 gives fair probabilities of 38.25% for the home win, 29.88% for the draw and 31.87% for the away win, which add back up to 100%. The fair odds are 2.61 (+161), 3.35 (+235) and 3.14 (+214).

The margin is not taken evenly in points. The home win loses 1.75 points (40.00 to 38.25), the away win 1.46 and the draw 1.37, because each outcome pays its share in proportion to its implied probability. A £10 bet on the home win at 2.50 returns £25, while the same bet at the exact fair price of about 2.615 would return about £26.15. That gap, repeated over hundreds of bets, is where the bookmaker's edge comes from.

Using fair odds to look for value

The most practical use of a no-vig price is as a benchmark. If one bookmaker's market says the fair price of the home win is 2.61 and another bookmaker offers 2.75 on the same outcome, the second price is higher than fair. Measured against the first market, the expected value of that bet is 38.25% x 2.75 - 1 = 5.2%. On a £10 stake that is an expected profit of about 52p per bet over the long run, not on any single result.

That sum only means something if the market you strip the margin from is a good estimate of the real chance. Markets with high limits and plenty of money behind them, close to kick-off or tip-off, tend to be sharper than early prices or niche markets. This is why bettors who track closing line value compare the price they took with the fair version of the closing price. Beating that fair price over a large sample is a sign the bets were made at good prices.

The same idea works the other way round. If you have your own estimate of a team's chance, the fair odds show whether the market agrees with you once its margin is removed. A gap of a point or two is easily within the error of most estimates. Value betting covers how to build an estimate and keep honest records of it, and the Kelly criterion calculator turns an edge into a stake size.

What the no-vig calculator does not cover

The tool assumes a single market with two or three outcomes where exactly one of them happens. Several common situations fall outside that.

• Markets with more than three outcomes. Outright winners, correct scores and top goalscorer markets have many selections. The formula is the same, so you can add every implied probability by hand and divide, but the calculator takes three prices at most.
• Lines that can push. A point spread or total on a whole number can land exactly on the line and refund your stake. The two prices do not show the chance of that push, so the fair probabilities describe the result if the bet is settled either way.
• Prices from different bookmakers. Taking the highest price for each outcome from several bookmakers measures something else, and the total can fall below 100%.
• Exchange commission. Back and lay prices on an exchange carry a commission on net winnings instead of a margin in the price, which the calculator does not include.
• Dead heats and void rules. Ties in golf or racing markets and void legs follow the settlement rules of the bookmaker you use.

The fair probability is also only as good as the market behind it. A margin of 8% on a minor league game or a niche prop tells you the bookmaker is less sure of the price, and the no-vig figure inherits that uncertainty.

Related guides and a quick check before you bet

How betting odds work explains fractional, decimal and American prices and how to convert between them. The implied probability guide goes further into adding up a market and reading the overround. To convert a single price and work out a return, use the odds calculator. The moneyline guide explains two-way and three-way match markets in detail.

Before you place the bet, run through a short routine:

• Enter every price of the market from one bookmaker and note the margin.
• Compare the fair odds with the price you plan to take, ideally against a sharper market close to the start.
• Treat a small difference as noise rather than a proven edge.
• Size the stake from a fixed bankroll; our bankroll management guide sets out simple staking plans.

Betting laws differ by country and, in the US, by state, and India has prohibited online money games since 1 May 2026, so check the rules where you live and use a licensed operator. If betting stops being fun, our responsible gambling page lists where to get help.