A same race multi, or SRM, is a fixed-odds bet that combines two or more outcomes in one race, such as Runner 1 to win and Runner 2 to finish in the top 2. It pays only if every leg lands, at one price the bookmaker quotes for the whole combination. The right price for it is not the leg prices multiplied, because outcomes in one race are linked: the runners share the same finishing places.
Racing NSW's reference manual (updated March 2025) lists the same race multi among fixed-odds bets, with the example of picking the winner and another horse to finish in the first four. Each bookmaker sets its own legs, limits and prices, so the arithmetic below is a way to check a price, not any bookmaker's method. Horse racing betting covers the bets an SRM sits beside.
The legs an SRM is built from
Each leg is a runner and a finishing band; each bookmaker's terms set which bands it offers:
| Leg | Lands if the runner finishes |
|---|---|
| Win | First |
| Top 2 | First or second |
| Top 3 | First, second or third |
| Top 4 | Anywhere in the first four |
Every leg has to land, so each leg you add lowers the chance of the whole bet, even one that looks safe, unless another leg already implies it. Some SRMs land on exactly the same results as an exotic bet, so the exotic's dividend is a second measure of what that result is worth:
| SRM legs | Lands on the same results as |
|---|---|
| Runner A win, Runner B top 2 | An exacta, A then B |
| Runner A top 2, Runner B top 2 | A quinella of A and B |
| Runner A top 3, Runner B top 3 | A duet of A and B, where a duet is run |
| Runner A win, Runners B and C top 3 | A trifecta with A first: 2 combinations |
| Runners A, B and C top 3 | A trifecta box of A, B and C: 6 combinations |
| Runners A, B, C and D top 4 | A first four box of the four: 24 combinations |
An exotic is usually a tote bet, paid a dividend declared after the race, so before the race you see only an approximate, while the SRM's price is fixed when the bet is accepted. A box spreads its outlay over its combinations, so set the SRM price against the exotic's dividend divided by the number of combinations. Horse racing bet types explains each exotic.
Why the leg prices are not multiplied
Multiplying prices is right only for independent outcomes, such as two winners in different races. Legs in one race are not independent, and the link can run either way.
Legs on different runners compete for places
Only one runner can win, and only two can fill the top 2. When Runner 1 wins, Runner 2 can no longer win, so its chance of a top 2 finish falls. A simple model, the Harville formula, puts a number on it: once one runner has won, each other runner's chance of second is its win chance divided by the chance left over. With illustrative chances of 35% for Runner 1 and 25% for Runner 2:
chance Runner 2 runs second if Runner 1 wins = 0.25 / (1 - 0.35) = 0.3846
That 38.5% is below Runner 2's 49.8% chance of a top 2 finish across all results (worked in the next section), so both legs together are less likely than the legs multiplied, and the fair SRM price is higher. Under that model, legs on different runners usually pull this way, harder the less likely each leg is. Two top 4 legs on well-fancied runners in a big field move little, but two on longer-priced runners, or a win leg with a top 2 leg, can cut the chance by a fifth or more.
Legs that overlap move together
The link runs the other way when one leg makes another more likely. The extreme case is two legs on one runner, such as Runner 1 to win and Runner 1 top 4. Every Runner 1 win is a top 4 finish, so the pair is worth exactly the win price, and multiplying by any top 4 price above $1.00 would pay more for the same result.
Bookmakers' terms decide whether that pair is offered, but it shows when an SRM pays less than its legs multiplied: overlapping legs land together more often than multiplication assumes. Real races also carry links the simple formula misses, so treat the model as a check. Correlated bets covers the idea across racing and sport, and same game multis shows the sports version.
An SRM price against the legs multiplied, worked
An illustrative six-runner race, with fair chances that add to 100% once the margin is taken out: Runner 1 35%, Runner 2 25%, Runner 3 15%, Runner 4 12%, Runner 5 8% and Runner 6 5%. The SRM is Runner 1 to win and Runner 2 top 2. Runner 2's top 2 chance is its 25% chance of winning plus its chance of running second behind each possible winner:
| Winner | Its chance | Runner 2 second if it wins | Both |
|---|---|---|---|
| Runner 1 | 0.35 | 0.25 / 0.65 = 0.3846 | 0.35 x 0.3846 = 0.1346 |
| Runner 3 | 0.15 | 0.25 / 0.85 = 0.2941 | 0.15 x 0.2941 = 0.0441 |
| Runner 4 | 0.12 | 0.25 / 0.88 = 0.2841 | 0.12 x 0.2841 = 0.0341 |
| Runner 5 | 0.08 | 0.25 / 0.92 = 0.2717 | 0.08 x 0.2717 = 0.0217 |
| Runner 6 | 0.05 | 0.25 / 0.95 = 0.2632 | 0.05 x 0.2632 = 0.0132 |
| Runner 2 second, in total | 0.2477 |
Runner 2 top 2 = 0.25 + 0.2477 = 0.4977, a fair price of 1 / 0.4977 = $2.01, and Runner 1 to win has a fair price of 1 / 0.35 = $2.86. Set side by side:
| Chance | Fair price | |
|---|---|---|
| The legs multiplied | 0.35 x 0.4977 = 0.1742 | 1 / 0.1742 = $5.74 |
| Both legs together | 0.1346, the first row of the table | 1 / 0.1346 = $7.43 |
Now an illustrative bookmaker: Runner 1 at $2.60 to win, Runner 2 at $1.85 top 2, and the SRM at $6.50. The leg prices multiply to 2.60 x 1.85 = $4.81, so the SRM pays 6.50 / 4.81 = 1.35 times its legs, about 35% more, which looks generous. Against the fair chance it is not:
EV per $1 = chance x price - 1 = 0.1346 x 6.50 - 1 = -0.125, about 12.5% below fair
That is the main trap: for legs on different runners, the multiplied legs understate the fair price, so an SRM can beat them easily and still carry a margin.
Risk: Betting involves risk. A fair chance from a model is an estimate, an SRM priced above it can still lose, and this one misses 1 - 0.1346 = 86.5% of the time. See responsible gambling for limits and support.
How same race multi odds are set, and how to check one
The bookmaker quotes one price for the combination, with its margin built in, from pricing it does not publish. You can check any SRM in four steps:
- Get a fair win chance for every runner from the exchange or a bookmaker's market: 1 / price for each, scaled so the field adds to 100%. That proportional method is the simplest of several, and others take more margin off longshots; the fair odds calculator runs four of them on up to 30 runners.
- Work out the chance that every leg lands together. For a win leg with a top 2 leg, use the table method above; for more legs, count through the finishing orders in a spreadsheet, or price the matching exotic.
- Compare: EV per $1 = chance of every leg landing x SRM price - 1. A negative number is what the bet costs you in margin, on average.
- Check the matching exotic where there is one, remembering that a tote dividend is not known until after the race.
When a runner in your SRM is scratched
After a late scratching, the Stewards order refunds on the scratched runner and declare deductions in cents in the dollar for winning fixed-odds bets struck before it; NSW's Rules of Betting set out the deductions in BR 14. Each bookmaker's terms set how a scratching changes an SRM; the common rule types are:
- Your runner is scratched: the leg is removed and the rest of the SRM stands at a price worked out again on the legs left, or the whole SRM is void and the stake refunded.
- Another runner is scratched late: the SRM stands, and a deduction can apply, because every other runner's chance has risen.
- The field shrinks: a top 3 or top 4 leg becomes far more likely in a small field, and some terms limit or void a leg below a set field size.
- A dead heat on the edge of a band, such as two runners tied for third in a top 3 leg. BR 16 of the Racing NSW Rules of Betting, for NSW on-course bookmakers, pays half the ticket's face value on a dead heat for first or the last paying place; on an SRM leg that would halve the return, so check your bookmaker's terms.
The same scratching can void one bookmaker's SRM and leave another's standing, so read the terms first. Scratchings and deductions and dead heat rules cover the general rules.
Bonus bets, price boosts and refunds on an SRM
Promotions change an SRM's value only where the bookmaker's terms let an SRM qualify. Three promotion shapes, with illustrative amounts and no bookmaker's actual offer, worked on the $6.50 SRM above with its 13.46% chance:
| Promotion shape | How it pays | On the fair chance |
|---|---|---|
| A $20 bonus bet used on the SRM | Winnings only: $20 x (6.50 - 1) = $110 if it lands | 0.1346 x $110 = $14.81, about 74% of the $20 face value |
| A price boost from $6.50 to $7.80 | $7.80 for each $1 if it lands | 0.1346 x 7.80 - 1 = +5.0% per $1 |
| A refund as a bonus bet if exactly one leg misses | Pays out when one leg lands and the other misses | One leg misses in (0.35 - 0.1346) + (0.4977 - 0.1346) = 0.5785 of races, about 58% |
The last row is worked on the linked chances, not the legs multiplied, and a refund paid as a bonus bet is worth less than cash. A bonus bet that loses pays nothing. Minimum odds, minimum legs and whether an SRM counts as a multi are set by each promotion's terms, and bonus bets on multis covers the bonus bet case.
Risk: Betting involves risk. A promotion changes the price, not the race: the boosted SRM still misses 86.5% of the time, and every promotion carries the bookmaker's own terms. See responsible gambling for limits and support.
Mistakes with same race multis
- Judging an SRM against its legs multiplied. The $6.50 SRM beat its $4.81 legs and still sat 12.5% below fair.
- Adding a near-certain leg. A top 4 leg on a strong favourite adds little to the price and a new way for the bet to lose.
- Skipping the matching exotic. A win and top 2 SRM lands on the same results as an exacta, so check the exacta's approximate first, knowing the declared dividend can differ.
- Skipping the scratching terms, then finding the bet void or re-priced after a late scratching.
Skip an SRM when one leg carries your whole opinion: a win bet on that runner pays its own price with no extra legs to miss.
Fair win chances on the Terminal
For step 1 of the check, the Terminal carries prices from 40+ bookmakers across racing and sports next to Betfair back and lay, and for racing it judges value against Betfair's own market. Those prices are read on a repeating cycle and shown as at the time displayed, so confirm any price with your bookmaker before you bet.
A free account opens a limited view of the Terminal with live odds, while Betfair prices begin at Terminal View; the pricing page compares the plans. Betfair is a trade mark of its owner, and B337 is not affiliated with it. For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au.
Risk: Betting involves risk. Exchange-based chances are estimates, not forecasts, and an SRM pays only when every leg lands. See responsible gambling for limits and support.