What the bookmaker's margin is, and how to measure it on a 1X2

The margin is how much the bookmaker keeps before paying out, and it takes one division and one sum. Turn every price into the probability it implies — 1 divided by the price — add them up, and subtract 1. What is left over is the margin.

On a 1X2 priced 2.00 / 3.40 / 4.00: 1/2.00 = 50%, 1/3.40 = 29.4%, 1/4.00 = 25%. The total comes to 104.4%, that is 4.4 points beyond the 100% of a perfectly fair market. Those 4.4 points are the margin: it is not a fee you see charged, it is already inside the price.

Why the total goes past 100%

In a three-outcome market the true probabilities add up to 100: one of the three things must happen. If a bookmaker paid exactly those probabilities, over time it would take in what it pays out. By shading every price down a little, the sum of the implied probabilities rises above 100%, and that difference is its structural margin.

From which a practical consequence: the margin doesn't tell you who will win, it tells you what it costs you to bet that market with that operator. It is the only number that compares two bookmakers without depending on the match.

What they actually keep: measured, not estimated

These are not textbook numbers: they are the median of the margins read from the three operators' own feeds, across the football listed on 13 September 2026 (572 matches). The median, not the mean, because a handful of exotic matches with very long prices would drag the mean without saying anything about the normal listing.

A dash is not a zero: it means that operator doesn't publish enough prices in that market for the measurement to mean anything. Where we don't measure, we don't write a number.

The market matters more than the bookmaker

The interesting reading is not the row, it is the column. With the same operator, Betsson, the full-time result costs 9.98% and Under/Over 6.95%: three points between two markets on the same match, decided only by where you put your money.

And the ranking between operators flips depending on the market: on the 1X2 the cheapest of the three is Betflag at 8.77%, but on Draw No Bet that same Betflag is the dearest at 11.85% against Betsson's 7.11%. Anyone picking «the bookmaker with the best odds» once and for all is answering the wrong question.

How steady it is over time

Across 46 daily readings between 30 July and 13 September 2026, Betsson's median 1X2 margin moved between 9.13% and 12.61%, with a median of 9.85%. It is not a constant: it rises when the listing fills with minor leagues, where the bookmaker has less information and protects itself more.

What to do with it

• Compare margins market by market: 1X2 against 1X2, Under/Over against Under/Over.
• A lower margin doesn't make a bet good: it makes the same bet less expensive.
• On a two-outcome market (both teams to score, Under/Over) margins are normally lower than on a 1X2, because there is one outcome fewer to cover.
• Look at the number on the match you care about, not on the average of the listing: the spread between competitions is wide.

Method and data: median of the implied probabilities minus 1, computed on the day's matches with at least five samples per market; Betsson and StarCasino share the group's odds feed and count as a single sample. The archive of readings is public and may be cited with attribution.