AFL Bookmaker Margin Calculator
Enter the prices in an AFL market and get the bookmaker margin, the total book percentage and the payout rate that market is offering. Compare it across bookmakers to see who is pricing footy tightest.
Margin Calculator
Inputs
Include every outcome in the market. A partial book always understates the margin.
Results
Margin of 4.05% across 2 outcomes
The market returns 96.10% of turnover if money lands on every outcome in proportion to its price.
- Book percentage
- 104.05%
- Margin
- 4.05%
- Payout rate
- 96.10%
Implied probabilities summed
Book percentage less 100%
Share of turnover returned
| Outcome | Decimal odds | Implied probability | Share of book |
|---|---|---|---|
| Outcome 1 | 1.85 | 54.05% | 51.95% |
| Outcome 2 | 2.00 | 50.00% | 48.05% |
How the AFL Bookmaker Margin Calculator works
Adding up the implied probability of every outcome in a market gives the book percentage. A book with no margin sums to exactly 100 per cent. Anything above that is the margin the bookmaker holds, which is the amount they keep if money lands on every outcome in proportion to its price.
Payout rate is the same information from the other direction: it is the share of turnover returned to punters across the market as a whole. A 4 per cent margin is a 96.1 per cent payout. Comparing margins across bookmakers on the same market is one of the more useful things you can do with a price, because it is the one component of the price that is entirely a choice the operator makes.
Book % = sum of (1 / odds) x 100 Margin % = book % - 100 Payout % = 100 / book % x 100
Example
An AFL head-to-head priced 1.85 and 2.00 gives implied probabilities of 54.05% and 50.00%, a book of 104.05%. The margin is 4.05% and the payout rate is 96.10%.
How to use it
- Enter the decimal price of the first outcome, for example 1.85.
- Enter the price of every remaining outcome in the same market, for example 2.00.
- Read the book percentage, the margin and the payout rate.
- Repeat with another bookmaker to compare margins on the same market.
AFL Bookmaker Margin Calculator FAQ
What is a typical margin on AFL markets?
Head-to-head, line and total markets on AFL matches are the most competitive and generally carry the lowest margins of any AFL market at a given bookmaker. Player prop markets and same game multis sit materially higher, and futures markets such as the premiership are higher again because they contain many outcomes and each one carries a share of the margin. Comparing the same market across operators is more informative than comparing different market types.
Does a lower margin mean better odds?
Across a whole market, yes: a lower book percentage means more of the turnover is returned. On a single selection it is not guaranteed, because a bookmaker can distribute the margin unevenly and offer a very competitive price on one side while holding more on the other. That is why comparing individual prices on the outcome you want is still worth doing, even after you have identified which operator generally runs the tighter book.
How does margin relate to expected value?
If every price in a market is fair relative to true probability, then backing any selection returns a negative expected value roughly equal to your share of the margin. On a two-way market with a 4 per cent margin that is about minus 2 per cent per bet. Beating a market therefore means finding a price that is longer than true probability by more than the margin sitting on it, which is why margin is the baseline any value claim has to clear.
Why do futures markets have such large margins?
Because the margin is spread across many outcomes, and each additional outcome contributes to the book total. An 18 team premiership market can run a book well above 110 per cent while each individual price still looks reasonable. The funds are also tied up for a long period, which operators price in. The result is that futures markets are structurally poor value relative to match markets, regardless of how attractive a single price looks.
Should I include every outcome when calculating the margin?
Yes. The book percentage only means anything if every possible outcome is included, because a partial book will always sum to less than the true total and understate the margin. On an AFL head-to-head there are two outcomes, so both prices are enough. On a market with a draw, a tie or a no result option, that outcome has to be in the sum too, or the margin figure will be misleadingly low.
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