How betting odds work: read a decimal price, see the chance behind it and price a multi

Odds look like a code until you see that a decimal price is only a multiplier. Everything on this page, from the bookie's margin to multis, comes from that one idea and some simple division. I've kept the maths to what a phone calculator can do.

A decimal price is what comes back for every $1

A price of $2.00 means every $1 you stake returns $2, and that $2 includes your own dollar. Bet $10 at $2.00 and a winner returns $20: your $10 back plus $10 profit. TAB puts it the same way: a $5 bet wins the advertised fixed odds multiplied by five.

So you need two short sums. Return is stake times price. Profit is stake times the price minus one. A losing bet returns nothing, whatever the price was.

The shorter the price, the more likely the bookie rates the result. The side at the shorter price is the favourite. The side at the longer price is the outsider, and punters call a long one a roughie.

Turn a price into a chance

Every price hides a percentage. Divide 1 by the price and multiply by 100: $1.50 gives 66.7%, $4.00 gives 25%. That figure is the implied chance, the rate at which the bet would break even if you placed it many times.

A few benchmarks save the calculator. $1.50 is two chances in three, $2.00 is a coin toss and $3.00 is one in three. At $5.00 it's one in five, and at $11.00 it's about 9%, or one in eleven.

It works the other way too. If you rate a side a 60% chance, its fair price is 1 divided by 0.60, or $1.67. That's how my ratings work: the calculator on the NRL tips page turns two club ratings into my price for both sides.

Implied chances hold up when you test them. In my 2026 NRL back-test, sides I priced at $1.50 or shorter won 72 of 107 games, or 67%. A $1.50 price implies 67%, so those favourites won about as often as their price said they would.

Why the two sides add up to more than 100%

Take an NRL game where a bookie has both sides at $1.90. Each price implies 52.6%, so together they make 105.3%. A real game can't add up to more than 100%. The extra 5.3% is the bookie's margin, also called the overround.

At fair prices, both sides would be $2.00. At $1.90, a winning $10 bet returns $19 instead of $20. That missing dollar is the bookie's cut, and it's built into the prices you see.

Uneven prices work the same way. Say the favourite is $1.30 and the outsider $3.60. That's 76.9% plus 27.8%, or 104.7% in total. Divide each chance by 1.047 to strip the margin out, and the fair prices come out near $1.36 and $3.77.

Each bookie sets its own margin, market by market. That's why the same side can carry a different price at different bookies on the same afternoon.

Head to head and line bets use the same maths

A head to head bet is the plainest market in footy: pick the winner. A line bet adds a points start. TAB describes it as picking the side that finishes ahead once the handicap is counted, so the underdog can lose the game and still win you the bet.

The number on a line is points, not a price. The price sits next to it and follows every rule above. If both sides of a line are $1.90, the margin is 5.3%, exactly as in the head to head example.

How multi odds work

A multi joins two or more bets into one, and every leg has to win. TAB's help page says the multi dividend is the prices of each selection multiplied together. So $1.50 and $2.00 make a $3.00 double, and a $10 bet returns $30.

Here is the four-leg NRL derby multi from my tips page, priced from my 2026 ratings. These are my prices, not a bookie's, so there's no margin in them yet.

Four sides that each look likely combine into a 20% chance. That's the part of a multi that's easy to skip: the chances multiply as well as the prices. A $10 multi at $5.07 returns $50.70 if all four land.

Why the margin grows with every leg

The bookie's margin multiplies too. Say each leg carries a 5% margin, so each price is the fair price divided by 1.05. One leg then returns about 4.8% less than a fair price would. Three legs return about 13.6% less, four about 17.7% less, and six about 25.4% less.

That's why I keep my own multis short. A long multi shows a big number, but with each leg you add, a bigger share of it stays with the bookie. Same game multis are priced differently again, because their legs are linked; the same game multi guide works through that.

Fractional and plus-minus odds

Some racing coverage and overseas sites still quote fractions. To convert one, divide the first number by the second and add one. So 6/4 becomes $2.50, 5/2 becomes $3.50, 14/1 becomes $15.00, and evens becomes $2.00.

US-style odds use plus and minus numbers. A plus number is the profit on a $100 stake, so +150 is $2.50. A minus number is the stake you need to win $100, so −200 is $1.50. TAB's own racing rules quote prices as decimals, like $1.90, and so does this site.

Reading prices on race day

Horse racing adds a second kind of price. Fixed odds work exactly as above. Tote prices are approximate dividends that keep moving until the race is run, because everyone's bets go into one pool and TAB takes its commission before paying out.

So a tote price on your screen is a guide, not a promise. The horse wagering guide explains how the pool works, how win, place and each-way bets pay, and why a place bet pays on two or three places depending on the size of the field.

What I look for in a price

I don't ask who will win. I ask whether the bookie's price is longer than mine. If I have a side at $1.80 and a bookie offers $2.00, the bookie is paying more than my ratings think the side is worth. That's the only bet that interests me.

My numbers are there to check, round by round, on how I tip, including the games the ratings got wrong. My AFL prices sit on the AFL tips page. Remember that a good price still loses often: a fair $2.00 side loses half the time.

Whatever you bet, set a deposit limit with your bookie first. If betting stops being fun, the responsible gambling page lists free support, including Gambling Help Online on 1800 858 858 and BetStop, the national self-exclusion register.

Harrison Yeo

Tips, ratings and prices for NRL and AFL

Published 29 September 2026 · Last checked 29 September 2026

What I did for this page: worked every example by hand, read TAB's help pages on head to head, line and multi bets, and priced the multi table from my 2026 NRL ratings (checked 29 September 2026). Not done yet: a side-by-side of live bookie prices on the same game, which waits for the 2027 draw.

How I tip · Sources for this page · How we make money. A bookie's commission doesn't change my ratings, my prices or the order of bookies.

Read next

• Same game multi explained: how an SGM is priced
• Horse wagering explained: tote, place terms and exotics
• NRL tips: my price for any matchup
• NRL multi tips: building a multi leg by leg
• Licensed bookies compared for footy