# What is the bookmaker's margin, and why do the three chances add up to more than 100? *For anyone who turned three prices into percentages, added them up and got 102. A plain guide to the margin, with this weekend's prices from Atlético v Barcelona and Forest v City as the worked examples.* Features · Published 01:42 ET, Nov 5, 2026 · Match News (https://matchnews.news/ca/features/what-the-bookmakers-margin-is/) By Features desk · Reviewed by Fredrik Jurek The bookmaker's margin is the gap between what the prices on a match add up to and 100. Turn each of the three prices on a match (home win, draw, away win) into a chance by dividing 1 by the price, add the three chances together, and the total comes to more than 100. If the true chances of the three results must add up to exactly 100, because one of them has to happen, then everything over 100 is not a chance at all. It is the bookmaker's margin: the slice built into the prices that the bookmaker keeps, on average, across all the bets it takes. A total of 102% means a margin of about two percentage points. That is the whole answer in one paragraph. The rest of this page answers the questions people ask next, with real prices from this site this week. ## Where does the margin come from? A bookmaker sets prices a little shorter than the true chances would justify. Suppose a coin is tossed and the bookmaker offers 1.90 on heads and 1.90 on tails. A decimal price, the format used on this site, shows what comes back for each unit staked, stake included, so 1.90 returns 1.90 for every 1 risked. The fair price on a fair coin is 2.00, because each side has a 50% chance. At 1.90 each side implies a chance of 1 divided by 1.90, which is 52.6%, and the two sides add up to 105.3%. Over many tosses, with equal money on each side, the bookmaker pays out 1.90 for every 2.00 it takes in and keeps the difference. That difference is the margin, and the 5.3 percentage points over 100 is how you see it in the prices. Nothing about the coin has changed; only the price is shorter than the chance. ## How do I work out the margin on a real match? Take Atlético Madrid against Barcelona in La Liga on Sunday 8 November, 21:00 CET. At 07:22 CET on Thursday 5 November, BettingBeast's feed, which this site reads at least once an hour, had Atlético at 3.87 to win, the draw at 4.55 and Barcelona at 1.85. Divide 1 by each price: 1 divided by 3.87 is 0.258, so 25.8%; 1 divided by 4.55 is 0.220, so 22.0%; 1 divided by 1.85 is 0.541, so 54.1%. Add them: 25.8 plus 22.0 plus 54.1 is 101.9. The three chances add up to 101.9%, so the margin on that market at that moment was about 1.9 percentage points. Do the same for Nottingham Forest against Manchester City on Saturday 7 November, 18:30 CET. At the same capture the prices were 4.83, 4.27 and 1.78. That gives 20.7%, 23.4% and 56.2%, a total of 100.3%, a margin of about a third of one percentage point. And for Napoli against Lazio on Sunday, 12:30 CET: 2.30, 3.77 and 3.22 give 43.5%, 26.5% and 31.1%, a total of 101.1%, a margin of about one point. So the margin is not one fixed number. It differs from match to match on the same morning, and it can change on the same match as the prices move. ## How do I strip the margin out? If you want the chances the prices imply with the bookmaker's slice removed, which some people call the fair chances, divide each implied chance by the total. For Atlético v Barcelona: 25.8 divided by 101.9 is 25.3%; 22.0 divided by 101.9 is 21.6%; 54.1 divided by 101.9 is 53.1%. Those three add up to 100. The order does not change, and the gaps between the results barely change; what changes is that each number is slightly smaller, because the slice has been taken out. This is the simplest method. There are others, which take more of the margin from the longer prices than from the shorter ones, but the simple division is close enough to read a match. Fair chances are still only chances. A fair 53% for Barcelona means that, by the price, something other than a Barcelona win happens in nearly half of games like this one. The margin does not tell you who wins. It tells you how much of the price is the bookmaker's and how much is the market's view of the game. ## Does the margin matter when I read a price move? Yes, in one specific way. When a price moves, this site measures the move in percentage points of implied chance, and a move of three points or more is treated as news. If the margin changes at the same time, the raw chances can move without the market's view moving at all. A simple check is to look at the total. If Barcelona went from 1.85 to 1.80 and the total went from 101.9% to about 103.4%, most of the apparent move would be a wider margin, not a stronger view of Barcelona. If the total stayed at about 102% and Barcelona still shortened, the view had moved. The Markets desk on this site watches both. ## Is a small margin always better for the person betting? A smaller margin means the prices pay out more for the same chance, so across many bets the bettor keeps more of their money. It is better in the way that a lower fee is better, and it is why people who follow prices look at the total as well as the price on the side they care about. It is not a reason to bet, and it changes nothing about the match. Betting at any margin loses money for most people over time, because the margin is the house's edge, and no price, however keen, turns a 54% chance into a certainty. ## Why is the margin on the goals line different? Every market on a match has its own margin, because each one is a separate set of prices. On Atlético v Barcelona the goals line, the number of goals that a bet on "over" or "under" is measured against, was 3.5 at the same capture, with over at 1.85 and under at 2.16. Those give 54.1% and 46.3%, a total of 100.4%, so a margin of less than half a point on a two-way market, against 1.9 points on the three-way match result. A two-way market often carries a smaller margin than a three-way one, and the margin on markets with many outcomes, such as the correct score or the first goalscorer, is usually larger still. The more outcomes a market has, the more room there is for the slice to hide. ## A worked example, start to finish Take Napoli against Lazio on Sunday 8 November at 12:30 CET, with the prices from 07:22 CET on Thursday: Napoli 2.30, the draw 3.77, Lazio 3.22. Step one, implied chances: 43.5%, 26.5%, 31.1%. Step two, the total: 101.1%. Step three, the margin: 1.1 percentage points. Step four, the fair chances: 43.0%, 26.2%, 30.8%. Step five, reading it: by the price, Napoli are favourites, the side given the better chance, at a little over two in five, with Lazio a little under one in three and the draw a little over one in four. Napoli are eighth in Serie A on 14 points and Lazio lead the table on 28, so the price is saying that home advantage and squad strength count for more than the table does this week. Whether it is right will be known at about 14:20 CET on Sunday. The margin is the one part of the arithmetic that is certain. ## In plain words The three chances on a match add up to more than 100 because the bookmaker builds a slice into every price. That slice is the margin. You measure it by turning each price into a chance, adding them, and seeing how far past 100 the total goes. You remove it by dividing each chance by the total. It differs from match to match and market to market, it changes as prices move, and it is why a price is never quite the true chance. Read the total as well as the price, and you will know how much of what you are looking at is the game and how much is the house. ## Sources 1. BettingBeast football prices, captured by this site's odds job (data/odds-latest.json and data/odds-series.json) (BettingBeast via Match News) https://matchnews.news/data/odds-latest.json - Read 01:28 ET, Nov 5, 2026 2. La Liga, Premier League and Serie A standings and fixtures (licensed feed, generated 2026-11-05T05:23Z, in data/latest.json) (football-data.org via Match News) https://www.football-data.org/ - Read 00:40 ET, Nov 5, 2026 --- 19+ (18+ in Quebec, Alberta and Manitoba). Gambling involves risk and can be addictive. Please gamble responsibly. Odds links go to BettingBeast. Match News is a football news site published by Checkraise Ltd. Every odds link on this site goes to BettingBeast. Articles are written with the help of an AI system and checked against the sources they cite; the responsible editor is named on every article.