Which Bets Has the Best Odds? Bookmaker Margins by Market in Australia
- The fairness of a bet type comes down to its bookmaker margin, which you find by adding the implied probabilities of every outcome.
- Evenly matched two-way markets, such as AFL or NRL head-to-head, usually carry the smallest margins.
- Racing win markets and same-game multis carry much bigger margins because more outcomes or stacked legs add more edge.
- Arbitrage locks mostly appear in low-margin markets, where small price differences between bookmakers can push the combined book under 100%.
- A lock only holds at the prices shown, because prices move, stakes get limited, bets can be voided and mistakes happen.
If you've searched which bets has the best odds, the honest answer comes down to one number: the bookmaker margin built into each market. Every Australian bookmaker prices its markets so they add up to more than 100%. The size of that excess changes a lot depending on the bet type. Head-to-head, line, racing win and same-game multis all carry different margins. Those differences explain where value sits and why arbitrage locks appear where they do. This guide works through each market with sample Australian prices and ranks them from tightest to widest. It also shows how comparing odds across licensed bookmakers can turn a low-margin market into a lock at the prices shown.
- What is a bookmaker margin, and how do you measure it?
- How do head-to-head and line markets compare?
- Why do racing win markets and same-game multis carry bigger margins?
- Which bets has the best odds? Ranking Australian markets by margin
- How does a best odds comparison site in Australia turn low margins into locks?
- What can go wrong, and how do you bet safely?
What is a bookmaker margin, and how do you measure it?
Every price a bookmaker offers carries a built-in edge, called the margin or overround. It's the reason an evenly matched game never pays even money on both sides.
To measure it, convert each decimal price into an implied probability by dividing 1 by the odds. Then add the results across every outcome in the market. A fair book adds to exactly 100%. Anything above that is the bookmaker's margin.
Take an NRL head-to-head priced at 1.90 and 1.95:
- 1 ÷ 1.90 = 52.63%
- 1 ÷ 1.95 = 51.28%
- Total: 103.91%, so the margin is about 3.9%
The lower that total, the closer you are to fair value. A market adding to 103% is kinder to punters than one adding to 115%, even if the individual prices in the wider market look attractive.
Two points are worth keeping in mind. First, the margin applies to the whole market, not to one selection. A bookmaker can shade the favourite and leave the outsider generous, or the reverse. Second, margins differ between bookmakers on the same event, which is why comparing prices matters.
This calculation is the foundation of everything that follows. Once you can add up implied probabilities on a phone calculator, you can rank any market type in seconds and see where value is most likely to sit.
How do head-to-head and line markets compare?
Head-to-head and line (handicap) markets are the two most popular ways Australians bet on AFL, NRL, NBA and tennis. Both are two-way markets, which keeps margins relatively low, but they behave differently.
Head-to-head on an even contest. When two teams are closely matched, prices such as 1.90 and 1.95 produce the 3.9% margin worked out above. Bookmakers compete hard on these popular markets, so the books often sit in a tight band.
Head-to-head on a lopsided contest. Shift to a heavy favourite at 1.25 against an outsider at 4.00 and the maths changes: 80% plus 25% equals 105%. Margins can widen when one side is short, because small price changes on the favourite carry a lot of implied probability.
Line markets. Line betting adds a points start to even things up, and prices are commonly shown at 1.90 each way. That works out to 52.63% twice, or 105.26%, a margin of about 5.3%. When a bookmaker offers 1.92 on both sides instead, the total drops to 104.17%, a noticeable improvement.
Totals. Over/under markets are often priced similarly to lines, so the margin tends to land in a comparable range.
The practical lesson is that there's no single answer for every game. An even head-to-head is frequently the tightest market on the board, but a well-priced line can beat a lopsided head-to-head. Do the sum rather than assuming.
Why do racing win markets and same-game multis carry bigger margins?
More outcomes usually mean more margin, and racing is the clearest example.
Here's an eight-runner race with plausible fixed-odds prices: 3.00, 4.00, 6.00, 8.00, 10.00, 12.00, 15.00 and 21.00. The implied probabilities are 33.33%, 25%, 16.67%, 12.5%, 10%, 8.33%, 6.67% and 4.76%. Add them up and you get 117.26%, a margin of more than 17%.
Every runner adds a slice of margin, and bookmakers often protect themselves on the longer-priced runners. Larger fields can push the total higher still. That doesn't make every race poor value, because individual runners can be generously priced at one bookmaker. But the overall book is much wider than a two-way footy market.
Three-way soccer markets sit in between. Home 2.40, draw 3.30 and away 3.10 add to 104.23%, a margin of about 4.2%.
Same-game multis are where margins compound. Each leg carries its own margin, and when legs are multiplied together, the margins multiply too. As an illustration, if three legs each carried a 5% margin, the combined book would sit at about 1.05 × 1.05 × 1.05, or roughly 115.8%. Bookmakers also price the relationship between legs themselves, and you can't see how they've done it.
That's why same-game multis can show eye-catching prices while offering less value per dollar than a single head-to-head. They're entertainment products, and the maths reflects that.
Which bets has the best odds? Ranking Australian markets by margin
Putting the worked examples together gives a rough ranking from tightest to widest margin. These are illustrative figures based on the sample prices above, not fixed rates. Real numbers vary by bookmaker, sport and event.
- Even head-to-head (AFL, NRL, tennis, NBA): about 3.9% in our example
- Three-way soccer result: about 4.2%
- Lopsided head-to-head: about 5%
- Line and totals at 1.90 each way: about 5.3%
- Three-leg same-game multi: about 15.8% from stacked margins alone
- Racing win, eight runners: about 17%
So on margin alone, two-way markets on major codes usually come out on top. Even contests that attract strong competition between bookmakers tend to be the tightest of all.
But the best market and the best price aren't the same thing. A racing field with a 17% overall margin can still contain one runner priced well above the rest of the market. That's why a best odds comparison across Australian bookmakers matters more than picking one market type and sticking with it.
A simple checklist before you bet:
- Add the implied probabilities for the full market
- Compare the same selection across several licensed bookmakers
- Prefer two-way markets when you want the lowest built-in edge
- Treat multis as entertainment, not value
How does a best odds comparison site in Australia turn low margins into locks?
A lock, or arbitrage, appears when the best available price on every outcome, taken from different bookmakers, adds to less than 100%. That's only realistic where margins start low. If each bookmaker's market sits near 104%, small disagreements between them can push the combined best prices under 100%. With a 117% racing book, prices have to disagree by a lot more.
Worked example. An NRL match is priced at 1.90 and 1.95 at one bookmaker. A second bookmaker has the home side at 2.06, while a third has the away side at 2.00.
- 1 ÷ 2.06 = 48.54%
- 1 ÷ 2.00 = 50.00%
- Combined: 98.54%, so roughly a 1.5% lock
With $1,000 to spread across both outcomes:
- Home stake: $492.60 at 2.06 returns $1,014.76
- Away stake: $507.40 at 2.00 returns $1,014.80
Either result returns at least $1,014.76, locking in roughly $14.76 at the prices shown.
A lock of that size is realistic. AUOdds data shows a typical lock of 1.5% over the last 30 days, from 3,149 locks found across 9 Australian bookmakers.
This is also why a best odds comparison site in Australia is useful even if you never chase an arb. Seeing every bookmaker's price side by side tells you where the market is tight and where one bookmaker has drifted. AUOdds tracks about 15,000 prices at any moment, with prices around 10 seconds old, because these gaps tend to close quickly.
What can go wrong, and how do you bet safely?
Low margins and locks don't remove risk. A lock only holds at the prices shown, and several things can break it:
- Prices move. If one leg changes before you place it, the lock can shrink or disappear.
- Stakes get limited. A bookmaker can cap how much you're allowed to bet, leaving one side unbalanced.
- Bets can be voided. A void on one leg, under the bookmaker's own rules, leaves you exposed on the other.
- Mistakes happen. The wrong market, wrong selection or a mistyped stake can turn a small edge into a loss.
Stick to licensed Australian bookmakers. ACMA has a page you can use to check whether a gambling operator is legal to offer services to Australians. Online in-play sports betting isn't available to Australians, so everything in this guide applies to pre-match markets only.
Keep clear records of your bets as well. The ATO's ruling on gambling and betting winnings is worth reading if you're unsure how your own situation is treated.
Finally, gambling is for adults 18+ only. Set a budget, take breaks and stop if it stops being fun. If you want to exclude yourself from licensed Australian online and phone wagering providers, BetStop, the National Self-Exclusion Register, is there for that. Confidential support is also available through Gambling Help Online at any time.
Frequently asked questions
Which bet type usually has the lowest bookmaker margin?
Two-way markets on major sports, such as an evenly matched AFL or NRL head-to-head, usually carry the smallest margins. In our sample prices, 1.90 and 1.95 produced a margin of about 3.9%. Lines and totals at 1.90 each way sit around 5.3%, while racing win markets and same-game multis are considerably wider.
How do I work out a bookmaker's margin myself?
Divide 1 by each decimal price to get the implied probability, then add the results for every outcome in the market. Subtract 100% and you have the margin. For example, 2.40, 3.30 and 3.10 in a soccer match add to 104.23%, a margin of about 4.2%. Lower totals mean fairer prices.
Are same-game multis bad value?
They're not built for value. Each leg has its own margin, and multiplying legs multiplies the margins, so a three-leg multi made from 5% legs carries roughly 15.8% before the bookmaker prices any relationship between legs. They can be fun for small stakes, but the maths favours the bookmaker more than a single head-to-head does.
What does a best odds comparison site in Australia actually help with?
It shows the same selection priced across several licensed bookmakers at once, so you can take the best price instead of the first one you see. When the best prices on every outcome add to under 100%, that's a lock at the prices shown. Prices move quickly, so check them right before placing anything.
Sources
- Check if a gambling operator is legal, Australian Communications and Media Authority
- BetStop: the National Self-Exclusion Register, Australian Communications and Media Authority
- BetStop, Australian Government
- Taxation Ruling IT 2655: gambling and betting winnings, Australian Taxation Office
More guides
18+ only. Betting involves risk, and prices and limits can change before you place a bet. If gambling isn't fun any more, Gambling Help Online (1800 858 858) is free and confidential, and BetStop lets you exclude yourself from every licensed Australian bookmaker.