A Melbourne Cup trifecta pays if you name the first three across the line in order, and with up to 24 starters that is one result out of 24 x 23 x 22 = 12,144. To cover more than one result you box runners or build a standout. A 5-runner box covers 60 combinations and a 6-runner box 120, which costs $60 or $120 at $1 a combination, or less as a flexi bet that collects a proportional share of the dividend.
Big fields are where flexi earns its place, and where it is easiest to spread a small outlay so thin that a winning ticket loses money. The tables below cost each structure for a full Cup field; trifecta betting explains the bet itself, and horse racing betting covers the other racing bets.
What a Melbourne Cup box trifecta costs
A box covers every finishing order of the runners in it, so for n runners boxed:
trifecta box combinations = n x (n - 1) x (n - 2)
flexi % = outlay / combinations x 100
| Runners boxed | Combinations | Full cost at $1 | Flexi on $20 | Flexi on $50 |
|---|---|---|---|---|
| 4 | 24 | $24 | 83.3% | 208.3% |
| 5 | 60 | $60 | 33.3% | 83.3% |
| 6 | 120 | $120 | 16.7% | 41.7% |
| 7 | 210 | $210 | 9.52% | 23.8% |
| 8 | 336 | $336 | 5.95% | 14.9% |
| 10 | 720 | $720 | 2.78% | 6.94% |
| 12 | 1,320 | $1,320 | 1.52% | 3.79% |
Each extra runner costs more than the last. Going from 6 runners to 7 adds 210 - 120 = 90 combinations, 75% more, so the same $50 falls from 41.7% to 23.8% flexi. A flexi above 100%, as with $50 on 4 runners, simply means more than $1 on each combination.
How flexi spreads a small outlay across more runners
Under the tote rules gazetted in WA in 2010, a flexi ticket puts the outlay divided by the number of combinations on each one, and a winning ticket is paid that share of the dividend.
With an illustrative trifecta dividend of $1,480.60 per $1:
| Ticket | Combinations | Flexi | Return if it lands |
|---|---|---|---|
| $50 on a 5-runner box | 60 | 83.3% | $1,480.60 x 50 / 60 = $1,233.83 |
| $50 on a 7-runner box | 210 | 23.8% | $1,480.60 x 50 / 210 = $352.52 |
The 7-runner box lands in more races, because it covers 150 more results, but when both land it collects 60 / 210 = 28.6% of what the 5-runner box does. Return = dividend x outlay / combinations, so a landed flexi ticket returns at least its outlay only when the dividend per $1 is at least the number of combinations. That is $60 for the 5-runner box, $210 for the 7-runner box and $1,320 for a 12-runner box.
Operators set their own minimum outlays and minimum flexi percentages and round flexi in their own way, so check your provider's terms before you build a ticket near a minimum. For any other box or standout, the flexi calculator counts the combinations and gives the percentage.
Risk: Betting involves risk. A wider box still loses whenever one of the first three is outside it, and a landed ticket comes back short of its cost any time the dividend falls below the number of combinations. See responsible gambling for limits and support.
Standouts and bankers in a big field
A structure narrows the box by fixing what you are surest of. The counts:
- Standout: one runner to win, with m others to fill second and third in any order, is m x (m - 1) combinations.
- Roving banker: one runner to finish anywhere in the first three, with m others for the other two places, is 3 x m x (m - 1).
- Position ticket: a runners for first, b for second (including the first-leg runners) and c for third (including the second-leg runners) is a x (b - 1) x (c - 2).
At the same $36 outlay:
| Ticket | Combinations | Flexi at $36 | Lands when |
|---|---|---|---|
| 6-runner box | 120 | 30% | Any three of your six fill the places, in any order |
| Standout: 1 to win, 6 for second and third | 6 x 5 = 30 | 120% | Your standout wins and two of the six run second and third |
| Roving banker with 6 others | 3 x 6 x 5 = 90 | 40% | Your banker runs first, second or third and two of the six fill the other places |
| 2 for first, 4 for second, 8 for third | 2 x 3 x 6 = 36 | 100% | One of your two wins, one of your four runs second and one of your eight runs third |
The flexi calculator's Custom layout counts each group as separate runners, so enter this position ticket as 2, 3 and 6, the a, b - 1 and c - 2 of the formula; typed as 2, 4 and 8 it counts 64 combinations.
A standout puts the whole outlay on one opinion, so its flexi is high, but if the standout does not win, all 30 combinations lose. The roving banker survives its banker running second or third, at a third of the standout's flexi. The position ticket spends where you think the order will fall. Trifecta strategy covers turning win prices into finishing-order chances before you choose a structure.
First four costs at the same outlay
A first four box covers n x (n - 1) x (n - 2) x (n - 3) orders, which is the trifecta box's count multiplied by (n - 3). At the same $50:
| Runners boxed | Trifecta combinations | Trifecta flexi at $50 | First four combinations | First four flexi at $50 |
|---|---|---|---|---|
| 4 | 24 | 208.3% | 24 | 208.3% |
| 5 | 60 | 83.3% | 120 | 41.7% |
| 6 | 120 | 41.7% | 360 | 13.9% |
| 7 | 210 | 23.8% | 840 | 5.95% |
| 8 | 336 | 14.9% | 1,680 | 2.98% |
A full field of 24 has 24 x 23 x 22 x 21 = 255,024 possible first fours. A first four standout with seven runners for second to fourth is 7 x 6 x 5 = 210 combinations, the same count as a 7-runner trifecta box. The break-even rule still holds: a 7-runner first four box needs a dividend of at least $840 per $1 to return its outlay. First four betting covers the bet in more depth.
Why big-field dividends vary so much
No figure tells you what a Cup trifecta will pay, and the mechanics show why:
- So many possible results. With 12,144 trifecta orders, many results carry little money, and when one of those lands, the few tickets holding it share the pool.
- Who fills the places. The pool, less the operator's commission, is shared among the winning units, so a result built from heavily backed runners is split many ways and one with outsiders in the places is split few ways.
- Jackpots. Under WA's 2010 gazetted tote rules, a trifecta or first four pool that no ticket wins may be added to a later pool of the same type (rule 13.2(a)), so a pool carrying that jackpot shares out more money on the same result.
- A pool that grows until betting closes. Approximates before the jump are estimates, and the dividend is declared after the result; tote approximates explains how to read them.
Scratchings and dead heats inside a Cup trifecta
WA's 2010 gazetted tote rules refund the share of a trifecta or first four ticket that covers a scratched runner. The Cup has no emergencies, so nothing replaces a horse scratched after the final field is declared; Melbourne Cup betting covers the field and the ballot.
Example: Illustrative. $36 on a 6-runner box is a 30% flexi. If one of the six is scratched, the 60 combinations that include it are refunded: 60 x $1 x 30% = $18 comes back. The remaining 5-runner box of 60 combinations stands at 30% as an $18 ticket.
Fixed-odds exotics follow the bookmaker's own terms. A dead heat for a place in the first three can make more than one order a winning one, and the operator's rules decide how the pool is shared, so check them. Exotic scratching rules covers substitutes and refunds across the exotics.
Mistakes with big-field exotics
With illustrative figures:
- Boxing too many runners for the outlay. Ten runners for $20 is a 2.78% flexi, so a $500 dividend returns $500 x 20 / 720 = $13.89, less than the $20 the ticket cost.
- Adding a runner without rechecking the flexi. Six runners to seven at $50 cuts the flexi from 41.7% to 23.8%.
- Copying a trifecta box into a first four at the same outlay. Six runners at $50 drop from 41.7% to 13.9%.
- Covering everything. A box of all 24 runners is 12,144 combinations, $12,144 at $1, to collect one dividend that can be smaller.
- Building under the minimum. A ticket below the operator's minimum outlay or flexi can be refused.
Using Cup win prices to choose who to leave out
With 24 runners, the first decision on a Cup ticket is which horses to leave out, and the win market is one place to start. B337's Terminal lists each runner's prices bookmaker by bookmaker, from 40+ bookmakers across racing and sports, picks out the best available price on each runner and sets Betfair back and lay beside it.
Those prices can feed the finishing-order method in the trifecta strategy guide. The choice of runners stays yours: B337 gives no ratings or selections, and no Cup dividend exists to compare until the tote declares it after the race.
The Betfair columns start with Terminal View, and plans and pricing compares the plans. A free account opens a limited view of the Terminal with live odds (see odds comparison), and credits, a per-bet usage charge, apply to any bet placed through B337. 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. A big-field exotic misses far more often than it lands, and a ticket that lands can still return less than it cost. See responsible gambling for limits and support.