Multi Leg / SGM Simulator
Enter your legs, run thousands of simulations, and see the real expected value of your multi. Pre-loaded with a 4-leg AFL SGM example.
How SGM Margins Compound
Each leg of a Same Game Multi carries its own bookmaker margin. When legs are combined, those margins multiply. A single leg at $1.90 might have a 5% margin. Four such legs combined can push the total margin past 20%. Bookmakers also apply a "correlation discount" on SGMs, meaning the odds are adjusted further when legs are linked (e.g. Team to Win + Over 160.5 points are positively correlated, so the combined odds are cut).
The true probability of all legs winning is the product of the individual win probabilities. The implied probability from the multi odds is always higher than the true combined probability - that gap is the margin the bookmaker keeps.
Why Multis Are Poor Value (But Still Popular)
A single-leg bet at $2.00 on a 50% chance breaks exactly even. A 4-leg multi where every leg is a 50% chance at $2.00 pays $16.00 but should be $16.00 at fair value. In practice, the multi odds are below $16.00 because each leg was priced with margin built in. The appeal is the large headline payout - a $20 bet returning $200+ looks exciting, but the expected loss on each attempt is significant.
SGMs add another layer: correlation between legs means a bookmaker model prices the combined outcome separately, and that price typically includes additional margin on top of the individual leg margins.
Frequently Asked Questions
What is the difference between a Multi and a Same Game Multi?
A standard Multi (also called a parlay) combines bets from different matches or events. A Same Game Multi (SGM) combines multiple legs from the same game - for example, Team to Win + a player to hit 25 disposals + Over 160.5 total points in one AFL match. SGMs carry extra margin because the bookmaker must account for correlations between the legs in the same event.
Why does adding more legs make the bet worse value?
Each leg you add multiplies the bookmaker margin, not just the probability. If one leg carries a 5% margin, two legs carry roughly 10% combined, four legs roughly 18-22%. The more legs you add, the more of your stake the bookmaker captures on average. The simulation above shows this clearly - the ROI and expected value deteriorate as legs are added.
What win probability should I enter for each leg?
Use your own estimate of the true probability - not the implied probability from the odds. For example, if a bookmaker offers a team at $1.70 to win, the implied probability is 1/1.70 = 58.8%. If you think the team's true win probability is 60%, enter 60. The gap between your estimate and the bookmaker's implied probability is your perceived edge on that leg.
This simulator uses random number generation and is for educational purposes only. Results do not predict future outcomes. Gamble responsibly. For free support call 1800 858 858.