Why they’re for mugs and why bookies love them


Multis. Is there anything more popular with today’s punters?

Most punters love multis because it gives them the chance of a big return.

But bookies love them even more, for a couple of reasons:

  • The fact that most punters, fundamentally, don’t understand odds
  • When you combine more than one selection in multis, the effect of the over-round in the market percentage compounds to your detriment.
The odds on multis

Because we’re smart punters, we understand that odds are merely an expression of probability. If we mark something a $1.20 chance, that’s because it’s an 83% cent chance of happening. 1 / $1.20 = 83%

So the $1.20 chance will win 5 out of 6, and it’ll lose 1 out of 6.

That’s simply compounded in a multi, which is why your price is compounded.

For a multi involving four $1.20 shots, you get odds of ($1.20 x $1.20 x $1.20 x $1.20 =) $2.07.

Most punters love those multis because on face value, they figure they’re getting $2.07 about a $1.20 shot.

They’re not.

The odds of that multi saluting are actually (83% x 83% x 83% x 83% =) 47%. Or just less than one in two. Which is why you’re getting $2.07.

So shift your mindset on multis. You’re not getting some huge value on a $1.20 shot. You’re simply taking a $2.07 shot.


And all of that is just based on 100% markets to make for a simple example. But bookies don’t offer 100% markets. They add on an over-round to make a profit. Before we go further, we’ll explain what the over-round is.

In essence, it’s the amount the bookie charges to take the bets.

We’ll start with the simplest example possible: a coin toss. There’s a 50% chance of the result being heads, and 50% chance of it being tails.

To convert the percentage into decimal odds, you just divide it into 1.

1 / 50% = $2.00

So your price for both heads and tails is $2.00 each. And that’s the price you get paid out. Imagine you and a mate make a $10 bet on the outcome of a coin toss: heads you win, tails he does.

You both put in your $10, and the winner gets paid $20 – odds of $2.00. Simple.

Now let’s say you and your mate have the same bet, but this time you employ a bookmaker to take and hold the money until the coin is tossed. Unfortunately for us punters, a bookie won’t do that job for free!

What the bookie does is increase the percentage on each selection, to include an amount for himself in the market. That’s the over-round.

Where the raw market had both the heads and tails at 50% each – $2.00 – the bookie may increase this to say, 54% each.

1 / 54% = $1.85.

That’s the odds for either a head or a tail. You and your mate put in your $10 each, but now the winner only gets paid out at $18.50. The bookie takes the $1.50 difference for himself: that’s his cut..

The total market percentage is now 108%: 54% + 54%. An 8% ocer-round. If the bookie wishes to take a bigger cut, he may increase the market percentage more. You’ll notice that each time the market percentage increases, odds decrease, meaning the winning punters get less and the bookie gets more.

The over-round on multis

And with multis, that over-round compounds. Put simply, you’re being charged a higher price to place your bet. If you’re making negative-EV bets (as most punters do) then you’re multiplying the edge against you with every leg. The flip-side is that if you’re making positive-EV bets (as professional punters do) then multis can actually be very profitable, since your edge compounds.

To try and explain this concept while keeping things as simple as possible, let’s use a simple, two-leg multi as the example.

Our first leg features Richmond playing Sydney, with both teams assessed to have an equal chance of winning.

The same situation applies in our second leg with the Broncos taking on the Storm. For the sake of simplicity, let’s say these teams are very even and are all are priced at $2.

However, back in the real punting world, bookmakers wouldn’t offer $2 about a true even shot. They’d probably offer $1.90, which represents a book of 105%.

There are four possible outcomes on the multi we are looking at:

  • Richmond / Broncos
  • Richmond / Storm
  • Sydney / Broncos
  • Sydney / Storm

The probability of any of the above combinations occurring is 1 in 4, which is true odds of $4.00. As mentioned earlier, we have deliberately kept this example simple by assuming that each outcome is equally likely.

Assuming a 100% book, a bet of $100 on any winning combination above would produce a return of $400, for a profit of $300.

But with a real world price of $1.90 for each leg, a bet of $100 would result in a return of $100 x $1.90 x $1.90. This return of $361 represents odds of $3.61, which is obviously far less than the true odds of $4.00.

This price of $3.61 represents a probability on that outcome of 27.7%, which we then multiply by four to allow for the total number of equally-likely outcomes.

We now have a 110.8% book, rather than the 105% book we had on a single bet. By combining two single bets, the over-round has more than doubled.

This massive increase in over-round (11% instead of 5% in our example above) makes it much more difficult for the punter to win on multis… and much easier for the bookie to win!

Is it any wonder so many bookmakers make multis such a focus of their marketing?

Punt like a pro with Trevor Lawson’s Melbourne Ratings.

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