What is the overround?

The amount by which the implied probabilities in a market exceed 100%. If home, draw and away imply 47.6%, 29.4% and 27.8%, the book is 104.8% and the overround is 4.8%.

Is this the same as a vig, juice or sportsbook margin calculator?

Yes. Overround is the British term, vig or juice the American one, and sportsbook margin or hold the industry’s; they all name the same thing — the amount by which a market’s implied probabilities exceed 100% — and this calculator computes it for any market in any odds format.

Is the margin the same as the bookmaker’s profit?

Only if the bookmaker takes a balanced book, which it rarely does. The margin is the edge built into the prices; the profit on a market depends on where the money went and what won.

What is a typical margin in football?

Around 2 to 3% on the match result at the sharpest bookmakers and exchanges, 5 to 8% at most high-street bookmakers, and higher again in niche markets such as correct score. Accumulators compound the margin of every leg.

How is the margin removed?

This calculator divides each implied probability by their total, which shares the margin across outcomes in proportion. Other methods (Shin, the power method) put more of it on the outsiders, which better reflects how bookmakers actually price longshots; the difference is small on short prices.

Free tool

Bookmaker margin calculator

How much of the market is margin, and what the prices would be without it.

Market

Home

Draw

Away

Margin removed proportionally (the multiplicative method). Prices in any format.

Bookmaker margin: 4.81%; the book adds to 104.8%
Home: implied → fair: 47.6% → 45.4%; fair price 2.20
Draw: implied → fair: 29.4% → 28.1%; fair price 3.56
Away: implied → fair: 27.8% → 26.5%; fair price 3.77

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Worked example

How much margin is in a match-result market of 2.10 / 3.40 / 3.60?

Prices (home / draw / away)	2.10 / 3.40 / 3.60
Implied probabilities	47.6% + 29.4% + 27.8%
They add up to	104.8%
Margin (overround): the excess over 100%	4.8%
Fair prices with the margin removed	2.20 / 3.56 / 3.77

The book keeps about 4.8% of the market; the fair prices are what the same view of the match is worth without it.

Why the margin matters more than the price

Two bookmakers can quote the same favourite at the same price and still be very different bets, because one has a 3% margin spread across the market and the other has 8%. The margin is the bookmaker’s edge before anything happens on the pitch, and it is paid on every bet, win or lose.

Comparing fair prices rather than quoted prices tells you which bookmaker is actually closest to the true odds. It also tells you how much better than the market your own probability has to be before a bet is worth anything: a 5% margin means a price that looks fair is really 5% short.

How this site uses de-vigged prices

The model is judged against the bookmakers’ de-vigged probabilities, not the raw prices: a selection has to clear the market’s own view of the chance, not just a price that was carrying a margin. The value finder compares the model’s price with the best available price the same way.

Questions

What is the overround?: The amount by which the implied probabilities in a market exceed 100%. If home, draw and away imply 47.6%, 29.4% and 27.8%, the book is 104.8% and the overround is 4.8%.
Is this the same as a vig, juice or sportsbook margin calculator?: Yes. Overround is the British term, vig or juice the American one, and sportsbook margin or hold the industry’s; they all name the same thing — the amount by which a market’s implied probabilities exceed 100% — and this calculator computes it for any market in any odds format.
Is the margin the same as the bookmaker’s profit?: Only if the bookmaker takes a balanced book, which it rarely does. The margin is the edge built into the prices; the profit on a market depends on where the money went and what won.
What is a typical margin in football?: Around 2 to 3% on the match result at the sharpest bookmakers and exchanges, 5 to 8% at most high-street bookmakers, and higher again in niche markets such as correct score. Accumulators compound the margin of every leg.
How is the margin removed?: This calculator divides each implied probability by their total, which shares the margin across outcomes in proportion. Other methods (Shin, the power method) put more of it on the outsiders, which better reflects how bookmakers actually price longshots; the difference is small on short prices.

The same numbers on real fixtures

The model’s probability for every fixture, by market: over 2.5 goals · under 2.5 goals · both teams to score · home wins · all of tomorrow’s matches.

The model does this arithmetic on every price it captures. Members see every pick it publishes, with the price, the stake and the reasoning, from the moment it is published. See what members get →

Other free tools

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A stake sized to the edge, with the fraction and cap we use ourselves.
Accumulator calculator
Combined odds, returns and the true chance of an accumulator landing.
Poisson football calculator
Expected goals in, match result, totals, both teams to score and likely scores out.

A calculator turns your numbers into other numbers. It does not know whether your numbers are right, and no arithmetic makes an outcome certain. Never stake money you cannot afford to lose.