Overround, Vig and Margin Explained – How to Calculate

Overround is how far the implied probabilities of every outcome in a market add up beyond 100%; that excess is the bookmaker's margin, also called the vig, vigorish or juice, and you calculate it by adding 1 ÷ odds for every outcome and subtracting 1.

The four words describe the same cost seen from slightly different angles (our value betting glossary defines each of them, plus 50 related terms, in one or two sentences). This article shows how to calculate it for two-way and three-way markets, how to read it from American odds, how much Pinnacle says it charges, and why the margin decides whether a price is worth betting.

Definition. The overround (or book) is the sum of the implied probabilities of all outcomes in a market. Margin is the overround minus 100%. Vig and juice are informal names for the same cost. A market with prices of 1.91 and 1.91 has an overround of 104.7% and a margin of 4.7%.

What is the overround in betting?

Every decimal price implies a probability: 1 divided by the odds. A price of 2.00 implies 50%, a price of 1.80 implies 55.6%. See implied probability explained for every odds format.

In a fair market the implied probabilities of all outcomes add up to exactly 100%, because one of them must happen. Bookmakers shade every price a little shorter than fair, so the total comes to more than 100%. That total is the overround. The part above 100% is what the bookmaker keeps, on average, if its prices are right.

How do you calculate the bookmaker margin?

The formula is the same for any number of outcomes:

Margin = (1/odds₁ + 1/odds₂ + … + 1/oddsₙ) − 1

Two-way market

Both sides at 1.91:

• 1 / 1.91 = 0.5236
• 0.5236 + 0.5236 = 1.0471
• Margin = 4.71%

Uneven prices work the same way. A tennis match at 1.25 and 4.20: 0.8000 + 0.2381 = 1.0381, a margin of 3.81%.

Three-way market (1X2)

Football win-draw-win prices of 2.50, 3.40 and 3.00:

• 1/2.50 = 0.4000
• 1/3.40 = 0.2941
• 1/3.00 = 0.3333
• Total = 1.0275, margin = 2.75%

The same match at 2.40, 3.30 and 2.90 gives 0.4167 + 0.3030 + 0.3448 = 1.0645, a margin of 6.45%. The prices look close. The cost is more than double.

You must include every outcome. Leave out the draw and the result is meaningless.

What is juice in American odds?

In American odds, the classic "-110 on both sides" spread is a two-way market at decimal 1.909 each.

• 1 / 1.909 = 0.5238
• 0.5238 × 2 = 1.0476
• Margin = 4.76%

To convert: a negative American price −X becomes 1 + 100/X in decimal; a positive price +X becomes 1 + X/100. Then apply the formula above. The free devig calculator does the conversion and the margin in one step. If the formats themselves are new to you, start with how to read betting odds.

Overround vs hold: are they the same?

Not quite. The overround is quoted as a share of the fair book (4.76% at -110/-110). The hold is the share of total stakes the bookmaker keeps if money is balanced: 1 − 1/1.0476 = 4.55%. Both describe the same prices. Margins quoted by bookmakers and tipsters often mix the two, which is why figures for the same market can differ by a few tenths of a percent.

Neither figure is what a bookmaker actually earns. Real results depend on which side the money lands, how prices move, and how the bets settle.

How much margin does Pinnacle charge?

Pinnacle's help centre says its markets average 102% (a 2% margin), compared with an industry average of around 106%. Source: Pinnacle Help Center, "What is a betting margin?", updated 25/03/2026, read 28/10/2026.

That is an average. Margins vary by sport, league and market. Main lines on big leagues are usually tightest; smaller leagues, props and exotic markets carry more.

A real example from Pinnacle Terminal on 28/10/2026: at 09:36:24, Pinnacle's Over 172.5 in BK Opava v TBB Trier (FIBA Europe Cup basketball) was priced 2.01, with a fair price of 2.112 after removing the margin (power method) and a limit of $250.

• Implied probability at 2.01: 49.75%
• Fair probability at 2.112: 47.35%
• Margin on that side: about 2.4 percentage points

If the Under carried a similar share, that market was close to 105%, well above the 2% average. A small-limit total in a second-tier European competition is the kind of market where you should expect a wider margin, even at Pinnacle.

Is the margin spread evenly across outcomes?

Usually not. Academic work on the favourite-longshot bias shows bookmakers tend to load more margin onto long shots than onto favourites. Hegarty and Whelan (University College Dublin working paper WP23/04, 2023) show that when this happens, bettors lose more on average than the simple overround suggests, especially on outsiders.

This is why there is more than one way to remove the margin. The multiplicative method assumes the margin is spread in proportion to probability. Additive takes an equal slice from each outcome. Power and Shin load more of it onto the outsiders. On a 1.91/1.91 market they agree. On a 1.25/4.20 market they do not. Our devig methods guide shows the four side by side.

Why does the margin matter for value betting?

Because it is the cost you have to beat. A soft book running a 6% margin can still post a price that is too long on one side, but its average price is worse than Pinnacle's. The way to tell is to remove Pinnacle's margin, get a fair price, and compare.

A worked example with round numbers. Pinnacle's two-way market is 1.95 / 1.95. Margin: 2 × (1/1.95) − 1 = 2.56%. Fair price for each side: 2.00. Your bookmaker offers 2.05 on one side.

• Edge = 2.05 / 2.00 − 1 = +2.5%
• The same bookmaker's market might be 2.05 / 1.80, a margin of 4.33%. It is expensive overall and still long on one side.

That is the whole logic of using Pinnacle as a sharp reference price: the bookmaker's total margin tells you how expensive it is in general; the comparison with a fair price tells you whether one specific price is worth taking. Soft books, as our soft bookmakers list notes, tend to run higher margins and react late to Pinnacle's moves.

What about betting exchanges?

On an exchange such as Betfair, the best back prices across outcomes usually sum close to 100%. The cost comes as commission on net winnings instead of a margin built into the price. To compare an exchange price with a bookmaker's, adjust the exchange odds for commission first: at 5% commission, a back price of 2.10 pays like 1 + (1.10 × 0.95) = 2.045.

Common mistakes

• Leaving out an outcome. The draw in football, or the "no" side of a prop.
• Comparing margins across different lines. A total of 2.5 and a total of 2.75 are different markets.
• Using a margin to judge one price. A low-margin market can still have a wrong price; a high-margin market can still have a long one. Remove the margin, then compare.
• Treating the overround as the bookmaker's actual earnings. It is a quoted figure, not a result.

How Pinnacle Terminal handles this

Pinnacle Terminal shows the fair price (NVP) next to every Pinnacle line in real time, calculated with four devig methods (multiplicative, additive, power and Shin) plus a worst case that takes the least favourable fair price. You choose the method on screen, and the fair price in each Telegram alert updates as the market moves. The CLV tracker compares the odds you took with the de-vigged closing price, not the raw one. See the closing line value guide for why that matters.

FAQ

What is a good bookmaker margin?

Lower is better for the bettor. Pinnacle says it averages 2% (102%) and puts the industry average at around 6%. On main two-way markets, anything under 3% is tight.

Is vig the same as overround?

In everyday use, yes: both describe the bookmaker's built-in cut. Strictly, overround is the total implied probability (for example 104.76%), and the vig or margin is the part above 100%.

How do I calculate the margin in a 1X2 market?

Add 1 ÷ odds for home, draw and away, then subtract 1. For 2.50, 3.40 and 3.00 the total is 1.0275, a margin of 2.75%.

Why do odds of -110 on both sides mean a 4.76% margin?

-110 is 1.909 in decimal. 1/1.909 is 52.38%, twice that is 104.76%, so the margin is 4.76%.

Can the overround be below 100%?

On a single bookmaker, almost never. Across different bookmakers, the best prices can add up to less than 100%; that is an arbitrage.

Try it

See Pinnacle's fair price on every line, with the margin removed four ways: start the Pinnacle Terminal 7-day free trial. Nothing is charged before day 8.

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