AFL Same Game Multi Calculator
Enter each leg of an AFL same game multi and the price the bookmaker is quoting, and see how far the quoted price sits below the independent price and how much extra margin that represents.
SGM Calculator
Inputs
2 of 8 legs, all from the one match
The single price the bookmaker is offering for the whole combination.
Results
Quoted price sits 16.27% below the independent product
Legs from the same match are correlated, so the product of the legs is a reference point, not a fair price. The gap below covers both the correlation adjustment and the bookmaker margin, and from outside the two cannot be separated.
- Independent price
- 4.18
- Quoted SGM price
- 3.50
- Price difference
- 16.27%
- Implied probability gap
- +4.65%
Legs multiplied together
Quoted price against the independent product
23.92% independent against 28.57% quoted
| Leg | Decimal price | Implied probability |
|---|---|---|
| Leg 1 | 2.20 | 45.45% |
| Leg 2 | 1.90 | 52.63% |
| Independent product | 4.18 | 23.92% |
| Quoted SGM | 3.50 | 28.57% |
This is a comparison, not a fair price. Pricing the same legs at several bookmakers and comparing each quoted price against the same independent product is the like for like use of it.
How the AFL Same Game Multi Calculator works
A same game multi combines legs from a single match, which means the legs are correlated. Bookmakers price an SGM with a correlation model rather than by multiplying the legs, so the quoted price is almost always shorter than the independent product. That shortening is partly a genuine correction for correlation and partly extra margin, and from the outside the two are not separable.
This calculator does not claim to know the true correlated price. It shows the arithmetic gap: what the legs would combine to if they were independent, what the bookmaker is actually offering, and the difference expressed both as a discount and as a change in implied probability. That gives you a like for like way to compare the same SGM across bookmakers.
Independent price = leg 1 x leg 2 x ... x leg n Discount = 1 - (quoted price / independent price) Implied probability = 1 / price
Example
Two legs at 2.20 and 1.90 combine to an independent price of 4.18. A bookmaker quoting 3.50 on the same game multi is offering a price 16.27% shorter, moving the implied probability from 23.92% up to 28.57%, a difference of 4.65 percentage points.
How to use it
- Enter the decimal price of each leg within the same match, for example 2.20 and 1.90.
- Enter the same game multi price the bookmaker is quoting, for example 3.50.
- Read the independent price and the discount applied to it.
- Repeat with prices from another bookmaker to compare the same combination.
AFL Same Game Multi Calculator FAQ
Why is an SGM price always shorter than the legs multiplied together?
Because legs from the same match move together. If a team wins comfortably, its midfielders are more likely to have racked up disposals and its forwards more likely to have kicked multiple goals. Treating those events as independent overstates how unlikely the combination is, so the independent product is too long a price. A bookmaker corrects for that with a correlation model. The correction is real, but the size of it is set by the bookmaker and includes their margin.
Can I tell how much margin is in an SGM?
Not exactly, because you cannot see the correlation model behind the price. What you can do is compare. Price the same combination of legs at several bookmakers and compare each quoted price against the same independent product. A book that consistently quotes a shorter price for the same legs is holding more margin or applying a heavier correlation adjustment, and either way you are being offered less. Published research on SGM markets generally puts the effective margin well above single-leg markets.
Are some SGM combinations more correlated than others?
Yes, and the direction matters. Backing a team to win alongside a high disposal line for one of its midfielders is positively correlated, so the fair combined price is shorter than independent. Backing a team to win alongside an under on the total match score can be negatively correlated in some situations, where the fair price would be longer than independent. Bookmakers apply the adjustment in both directions, but the discount on positively correlated combinations is the one punters meet most often.
How does a voided leg work in a same game multi?
Treatment varies more than it does on a standard multi, because removing a leg changes the correlation structure of the rest. Some bookmakers void the entire SGM if any leg is voided, others re-price the remaining legs through their model at the original stake. A late withdrawal in an AFL player prop leg is the most common trigger. Because the outcomes differ so much between operators, check the specific terms before placing an SGM that includes a player market.
Should I use the multi calculator or the SGM calculator?
Use the multi calculator when your legs come from different matches, where multiplying the prices is a fair model of the combined bet. Use the SGM calculator when the legs come from one match, because then the product is only a reference point and the number that matters is what the bookmaker is quoting against it. The SGM calculator is a comparison tool: it tells you how a quoted price relates to the naive price, not what the fair price is.
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