On ordinary bookmaker prices, multis are not worth it for value: a multi multiplies every leg's margin, so on average it returns less per dollar than the same legs bet as singles. In the worked example below, three legs that return 95.2, 96 and 96 cents per dollar as singles return about 87.7 cents together.
A multi earns its place when you rate every leg above its price, because then the edges multiply instead of the margins. How betting odds work explains the margin each leg carries.
What a multi returns against the same legs as singles
Take three legs from three unrelated games, with illustrative prices and your estimate of each true chance. Average return per $1 = true chance x price:
| Leg | Price | Your estimate of the chance | Average return per $1 |
|---|---|---|---|
| Leg 1 | $1.70 | 56% | 0.56 x 1.70 = 0.952 |
| Leg 2 | $2.00 | 48% | 0.48 x 2.00 = 0.960 |
| Leg 3 | $2.40 | 40% | 0.40 x 2.40 = 0.960 |
| The multi | 1.70 x 2.00 x 2.40 = $8.16 | 0.56 x 0.48 x 0.40 = 10.75% | 0.952 x 0.960 x 0.960 = 0.8774 |
The multi's average return is the legs' returns multiplied. With $60 to spend:
| $60 spent | Three $20 singles | One $60 multi |
|---|---|---|
| Return if all three win | $34 + $40 + $48 = $122.00 | 60 x 8.16 = $489.60 |
| Chance of a profit | 46.98% (two or more legs win) | 10.75% (all three win) |
| Chance of losing all $60 | 0.44 x 0.52 x 0.60 = 13.73% | 1 - 0.1075 = 89.25% |
| Average return | 20 x (0.952 + 0.960 + 0.960) = $57.44 | 60 x 0.8774 = $52.64 |
| Average result | -$2.56, about 4.3% of $60 | -$7.36, about 12.3% of $60 |
The singles profit when two or more legs win: 0.36224 for exactly two (worked below) plus 0.10752 for all three = 0.46976.
Void legs, scratchings and dead heats are settled under each bookmaker's terms. For NSW-authorised sports bookmakers, clause 5.1.9 of the Bookmaker Declared Betting Events Betting Rules pays a multi whose remaining event is abandoned on the legs already won. If Leg 3's game were abandoned after Legs 1 and 2 had won, the $60 multi would return 60 x 1.70 x 2.00 = $204. Multi bets explained covers the other cases, and the multi bet calculator works out a multi's return from its legs.
Probability of landing: multiply the true chances
For independent legs, such as legs from unrelated games, the chance that every leg wins is the product of their true chances. Legs from different events can still be linked, such as a team's knockout final and its premiership. Here that is 0.56 x 0.48 x 0.40 = 0.1075, about one ticket in 9.3 (1 / 0.1075). The price's implied probability is 1 / 8.16 = 12.25%, which is what the legs' implied chances (1 / 1.70, 1 / 2.00 and 1 / 2.40) multiply to. The gap between 12.25% and 10.75% is three margins, compounded.
With illustrative legs that each have a true 55% chance at $1.75, so each returns 0.55 x 1.75 = 96.25 cents per dollar:
| Legs | Multi price | Chance it lands | Lands about once in | Average return per $1 |
|---|---|---|---|---|
| 1 | $1.75 | 55.00% | 1.8 tickets | 96.25c |
| 2 | $3.06 | 30.25% | 3.3 tickets | 92.64c |
| 4 | $9.38 | 9.15% | 10.9 tickets | 85.82c |
| 6 | $28.72 | 2.77% | 36.1 tickets | 79.51c |
Each extra leg multiplies the price by 1.75, the chance by 0.55 and the return by 0.9625. Six such legs land together about once in 36 tries and lose about 20.5 cents in every dollar on average, returning 79.51 cents.
Why the bookmaker likes multis
A multi is a chain of all-up bets: each winning return is bet again on the next leg. On the $60 multi, $60 rides on Leg 1. If it wins, its $102 return rides on Leg 2, and if that wins, $204 rides on Leg 3. Every link in the chain pays that leg's margin.
Averaged over every result, the money riding on each leg is $60, then 60 x 0.56 x 1.70 = $57.12, then 57.12 x 0.48 x 2.00 = $54.84. That is about $172 of betting from $60 of your money. Charge each leg's cost on what rides on it, 60 x 0.048 + 57.12 x 0.04 + 54.84 x 0.04, and it comes to about $7.36, the multi's whole average loss. The same $60 as singles passes through the margins once and costs $2.56.
So $60 carries close to three times its size through the margins, and one losing leg keeps the lot. Bookmaker margin shows how to measure each leg's margin.
When a multi can make sense: legs you rate as value
Compounding works in your favour when every leg is a value price, one above its true chance. Keep the three prices, but say your estimates are higher:
| Leg | Price | Your estimate | Average return per $1 |
|---|---|---|---|
| Leg 1 | $1.70 | 62% | 0.62 x 1.70 = 1.054 |
| Leg 2 | $2.00 | 53% | 0.53 x 2.00 = 1.060 |
| Leg 3 | $2.40 | 44% | 0.44 x 2.40 = 1.056 |
| The multi | $8.16 | 0.62 x 0.53 x 0.44 = 14.46% | 1.054 x 1.060 x 1.056 = 1.1798 |
As singles, the $60 now averages $63.40 back (20 x 3.17), about 5.7% profit. As a multi it averages 60 x 1.1798 - 60 = $10.79, about 18%, roughly three times the singles' edge. Value betting covers how to test estimates like these.
Two things cut into that. An error in your estimates compounds as fast as an edge: if the true chances are the 56%, 48% and 40% of the first table, the same ticket averages a 12.3% loss. And the multi still lands only 14.46% of the time, about once in 6.9 tickets.
A multi fits when you rate every leg as value, the legs are unrelated and the stake is small. Singles usually fit better when only some legs are value. Legs from one game are usually linked, so their chances do not simply multiply, as correlated bets explains.
Risk: Betting involves risk. An edge built on your own estimates is only as good as they are. A multi of value legs still loses about six tickets in seven on these numbers, and there is no guarantee of profit. See responsible gambling for limits and support.
Variance: how often a multi lands, and what a near miss pays
A near miss pays nothing. In the first example exactly two legs win 0.56 x 0.48 x 0.60 + 0.56 x 0.52 x 0.40 + 0.44 x 0.48 x 0.40 = 0.16128 + 0.11648 + 0.08448 = 36.22% of the time. As singles those results return $74, $82 or $88 on the $60; as a multi they return $0.
Long runs without a winner are normal. The chance of one is the chance of a loss raised to the length of the run:
| Bet (illustrative) | Chance it wins | Chance of 10 losers in a row |
|---|---|---|
| A single at a 53% chance | 53.00% | 0.47 to the power 10 = 0.05% |
| The value multi | 14.46% | 0.8554 to the power 10 = 21.0% |
| The ordinary multi | 10.75% | 0.8925 to the power 10 = 32.1% |
Variance in betting and losing streaks show how far such swings run.
Bankroll implications of betting multis
Size a multi stake from the losing run it has to survive, not from the payout. At a flat $20 a ticket, 20 losing multis in a row cost $400, and on the ordinary multi that happens about one time in ten (0.8925 to the power 20 = 10.3%). Bankroll management covers setting a stake as a small share of your betting money.
Behind any plan, set a hard cap: Australian online bookmakers must offer deposit limits, and under the National Consumer Protection Framework a decrease applies at once while an increase applies only after 7 days. Never raise stakes to win back losing tickets, which chasing losses explains.
Promotions that change a multi's value
Promotions built for multis change the sums by their shape, never the chance that every leg wins.
- A winnings boost adds a percentage to a winning multi's profit, under conditions such as a minimum number of legs. An illustrative 10% boost makes the $8.16 multi pay 1 + 7.16 x 1.10 = 8.876 times the stake, and 0.1075 x 8.876 = 0.954: still a loss of about 4.6% per dollar. Odds boosts explained covers the other types.
- A refund if one leg fails, in cash or as a bonus bet, pays on near misses: 36.22% of the time on the first example's legs. Multi insurance explained values one, caps included.
- A bonus bet pays the winnings only, so a longer multi price keeps more of its face value until the compounding margins take it back, as bonus bets on multis shows.
Every promotion carries its bookmaker's own terms, and the bookmaker decides whether a multi qualifies.
Risk: Betting involves risk. A promotion changes the price, not the chance: the boosted multi still lands about once in 9.3 tickets, and a bonus bet that loses pays nothing. See responsible gambling for limits and support.
Mistakes that make multis cost more
With the illustrative legs above:
| Mistake | What it costs | The fix |
|---|---|---|
| Adding a short leg as a banker | An illustrative $1.20 leg you rate at 80% lifts the price to 8.16 x 1.20 = $9.79, but cuts the chance to 0.1075 x 0.80 = 8.60% and the return to 0.8774 x 0.96 = 84.2 cents | Add a leg only if you rate it above its price |
| Reading the price as the chance | 1 / 8.16 = 12.25% overstates the 10.75% the true chances give | Multiply the true chances, not the implied ones |
| Raising stakes after a losing run | A 10-ticket losing run comes about one time in three on the ordinary multi | Keep stakes flat and within your limits |
Checking leg prices on B337's Terminal
A multi is struck at one bookmaker, so it cannot mix the best price on each leg the way singles can, but you can check each leg's price first where the Terminal carries that market. The Terminal shows racing and sports prices from 40+ bookmakers side by side, with the best available price on each selection picked out beside exchange back and lay prices. From Terminal View, EV overlays compare each price with an estimated fair price, an estimate rather than a forecast.
The Terminal reads prices on a repeating cycle, not tick by tick, so confirm each leg in your bookmaker account before you bet. A free account opens a limited view of the Terminal with live odds, and the pricing page lists what each plan adds. For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au.
Risk: Betting involves risk. A leg priced above its fair estimate can still lose, one losing leg loses the whole multi, and bookmakers can restrict accounts and void bets. See responsible gambling for limits and support.