Boxed trifecta calculator: cost, flexi % and payout

Trifecta calculator

Combinations: -
Cost for 100%: -
Your flexi %: -
You would collect: -

Key facts

A trifecta pays if you pick the first three runners in exact order. A boxed trifecta covers your runners finishing 1st, 2nd and 3rd in any order.
Combinations in a box = n x (n - 1) x (n - 2): a 4 horse box is 24 combinations, a 5 horse box is 60.
Flexi % = your outlay / full cost x 100. $15 on a 5 horse box ($60 for 100%) is 25%, so you collect 25% of the $1 dividend.
The TAB's minimum is 50 cents, in 50 cent steps, and the flexi percentage must be at least 1%.
In a 24 runner Melbourne Cup field, even a 6 horse box covers only 120 of the 12,144 possible trifecta results.

How to use the boxed trifecta calculator

Choose a boxed trifecta and pick how many runners are in your box, or switch to standout to type runner numbers for each position. Enter what you want to spend. The calculator shows the number of combinations, the full cost at $1 a combination, your flexi percentage and, once you enter a dividend, what you would collect.

What a trifecta bet is

A trifecta is a bet on the first three runners in exact order. Get 1st, 2nd and 3rd right and you share the trifecta pool with everyone else who did. It is a tote bet, so the dividend is only known after the race and depends on how much was bet and how many people picked the result.

A boxed trifecta covers every order of the runners you choose. Box 3, 5 and 8 and you win if those three fill the places in any order: 3-5-8, 8-3-5 and so on.

How many combinations a box covers

The number of combinations is n x (n - 1) x (n - 2), where n is the runners in your box. That is why the cost climbs so fast.

Runners boxed	Combinations	Cost at 100%	$24 outlay is
3	6	$6	400%
4	24	$24	100%
5	60	$60	40%
6	120	$120	20%
7	210	$210	11.43%
8	336	$336	7.14%
10	720	$720	3.33%

Flexi betting: spend what you want

Flexi betting means you choose the outlay and get a matching share of the dividend. The TAB works it out as your stake divided by the cost of the bet at $1, times 100. Its own example: a 5 runner trifecta box costs $60 at 100%, so a $15 bet is 25% and pays 25% of the dividend.

The TAB's minimum investment is 50 cents in 50 cent steps, and the percentage has to be at least 1%.

Pundit tip: a bigger box is not a smarter bet by default. It raises the cost of every winning combination you already had. Cut the runners you would not be upset to lose.

Standout and custom trifectas

A standout trifecta puts your strongest pick in one position and boxes the rest behind it, which cuts the cost. Switch the calculator to standout and type runner numbers for each position. It removes impossible combinations, such as the same runner in two places, and counts what is left.

Bet	Combinations
Box 3, 5, 8, 11	24
3 to win, 5, 8, 11 for 2nd and 3rd	6
3 and 5 for 1st, 3, 5, 8, 11 for 2nd and 3rd	12

The Melbourne Cup trifecta in numbers

The Melbourne Cup runs at Flemington on Tuesday 3 November 2026 over 3200 metres, and the field is limited to 24 runners. With 24 starters there are 24 x 23 x 22 = 12,144 possible trifecta results. A 6 horse box covers 120 of them, under 1%. That is why Cup trifectas often pay big dividends, and why most boxes lose.

Read the full Melbourne Cup betting guide for every bet type on Cup day. For cheaper exotics, try the quinella calculator; for the first four placegetters, use the first four calculator. To pick the winners of four races instead, our quaddie guide shows how the cost grows with every runner you add. Trifectas are not only a gallops bet: see greyhound betting and harness racing betting for the dogs and the trots. If runners tie for a place, our dead heat rules guide explains how a tie splits the payout.

Frequently asked questions

How much is a boxed trifecta?

A boxed trifecta costs $1 per combination for a full 100% unit. Three horses is 6 combinations ($6), four is 24 ($24), five is 60 ($60) and six is 120 ($120). With flexi betting you can spend less and take a share of the dividend.

How do I calculate a boxed trifecta payout?

Multiply the $1 dividend by your flexi percentage. If the trifecta pays $850 for $1 and you had a 5 horse box for $15 (25%), you collect $850 x 25% = $212.50.

What is a standout trifecta?

A standout trifecta fixes one runner in a position, usually first, and boxes others behind it. Runner 3 to win with 5, 8 and 11 for second and third is 6 combinations, much cheaper than boxing all four (24).

How much is a 7 horse box trifecta?

A 7 horse box trifecta is 210 combinations, so $210 for a full 100% unit. On a $21 outlay your flexi percentage is 10%.

What is a flexi trifecta?

Flexi lets you spend any amount on a trifecta instead of a fixed $1 per combination. Your outlay divided by the full cost gives your percentage, and you are paid that percentage of the dividend. The TAB requires at least 1%.