How we work it out

Short version: bookmaker odds contain a hidden fee. We do the sum that takes it out, and show you both the result and the size of the fee. Nothing here is secret — you can check every step with a calculator.

1. Odds are probabilities in disguise

Any price can be turned into a percentage by dividing 1 by it. A price of 2.00 becomes 1 ÷ 2.00 = 50%. A price of 4.00 becomes 25%. That is all an odd is: a chance, written differently.

2. The percentages never add up to 100

Take a match priced 1.91 on each side of a two-way market. Convert both: 52.4% and 52.4%. Added together that is 104.8% — impossible, because one of the two things definitely happens.

The extra 4.8% is the bookmaker's fee. It is called the margin, the vig, or the overround. It is charged whether you win or lose, and it appears on no receipt.

3. Taking it out

We divide every raw percentage by the total. That is the whole calculation:

52.4 ÷ 104.8 = 50.0%
52.4 ÷ 104.8 = 50.0%
Total: 100%

What is left adds up to exactly 100 and can be read as a real probability. This is the equal-margin method, sometimes called multiplicative de-vigging: each outcome gives up the same proportion of the fee.

4. Why we name the method

On a balanced market every de-vigging method agrees. On a lopsided one — a heavy favourite against a big underdog — equal-margin, odds-ratio, logarithmic and Shin all return different answers from identical prices.

A product whose entire claim is “the real percentage” cannot leave that implicit. We use equal-margin, we say so, and we show the fee separately so you can redo the arithmetic yourself if you disagree with the choice.

5. Where the numbers come from

We read the publicly displayed prices of the bookmaker that professional bettors use as their reference — the one whose prices other bookmakers follow. We are not affiliated with them, or with any operator. We take no wagers.

6. One honest limitation

On very large underdogs — below roughly 10% — the home/draw/away market runs slightly high, a long-documented quirk in how these prices are set. Handicap markets do not have it. If you bet longshots often, read the same match through the All handicaps tab.

And the number that matters most: matching the market's accuracy is not enough to profit. A bettor who beat the closing price in every single game of a season still wins only slightly over 51% — below the 52.4% needed to break even at standard odds. We show you the real chance. We do not claim it makes you money.