Arbitrage betting in Australia: how it works
- Arbitrage betting means backing every outcome of an event at different bookmakers, at prices that add up to a return whichever way it lands.
- The stake on each outcome is set by its odds, so every result pays back roughly the same amount.
- Typical locks return a few per cent of the total staked, so speed and repetition matter more than any single bet.
- The real risks are prices moving before you place, stake limits, voided bets and simple mistakes.
Arbitrage betting in Australia works because our bookmakers price the same events independently, and for a few minutes at a time their prices can disagree enough that you can back every outcome and still get more back than you staked. That combination of bets is called a lock, or an arb. It isn't a tip or a prediction: the maths is set before the event starts. This guide walks through how a lock works, how to size each bet, where locks come from, and the risks you need to manage.
What is arbitrage betting?
Every bookmaker builds a margin into its prices, so if you back every outcome at one bookmaker you'll always stake more than you get back. Arbitrage betting gets around that by taking the best price for each outcome from different bookmakers.
When those best prices are high enough, the chances they imply add up to less than 100%. That gap is your locked return. You stake a slightly different amount on each outcome so that whichever one wins, the payout is about the same.
This is why arbitrage bettors talk about locks rather than tips. A tip is an opinion about who will win. A lock doesn't care who wins: the return was set by the prices you took.
In Australia the opportunities come from a busy, competitive market. Dozens of licensed bookmakers price thousands of events every day across NRL, AFL, racing, tennis, basketball, soccer and smaller sports, and they don't all move their prices at the same moment.
How does a lock work? A worked example
Say a tennis match has two players. One bookmaker offers 2.10 on Player A, and another offers 2.05 on Player B.
- Implied chance of A winning at 2.10: 1 ÷ 2.10 = 47.62%
- Implied chance of B winning at 2.05: 1 ÷ 2.05 = 48.78%
- Total: 96.40%, which is under 100%, so there's a lock
With $1,000 to spread across both bets, you split it in proportion to those percentages:
- Stake on A: $1,000 × 47.62 ÷ 96.40 = $493.98
- Stake on B: $1,000 × 48.78 ÷ 96.40 = $506.02
If A wins, $493.98 × 2.10 pays $1,037.36. If B wins, $506.02 × 2.05 pays $1,037.34. Either way you get back about $1,037 from $1,000 staked, a locked return of about 3.7%.
That's a strong lock. Most are smaller, and they don't last: once a bookmaker moves its price, the gap closes. The skill is in finding locks quickly and placing both bets at the prices shown.
How do you calculate the stake on each outcome?
The rule is simple: each outcome's stake is proportional to 1 ÷ its odds. Divide your total by the sum of the implied chances, then multiply by each outcome's implied chance.
For three-way markets, such as soccer with a draw, the method is the same with three prices. If the three implied chances add up to 97%, the lock is worth about 3% of the total staked, spread across three bets.
A few practical points make a big difference:
- Round sensibly. Most bookmakers accept cents, but some prefer whole dollars. Round each stake so the payouts stay close to equal.
- Check the total before you place. If rounding tips one payout below your total stake, adjust.
- Place the harder bet first. If one bookmaker is more likely to limit your stake, place that leg first, then size the other legs to match what was accepted.
A calculator or an alert that already shows the exact stake for each outcome saves the most time. When prices move within seconds, working the numbers out by hand is often too slow.
Where do locks come from in Australia?
Locks appear when bookmakers disagree. Common causes include:
- Different reactions to news. Team changes, injuries and scratchings reach each bookmaker's traders at slightly different times.
- Different risk positions. A bookmaker holding a lot of money on one side may lengthen the other side to attract bets.
- Smaller markets. Table tennis, lower-league soccer and overseas tennis get less trading attention, so prices drift further apart.
- Specials and boosted prices that sit above the rest of the market for a while.
They're more common than most people expect. AUOdds data shows 176 locks alerted to members in the last 30 days, with a typical lock of about +2.7%. Most last only minutes, and many disappear in under a minute once other bettors or the bookmaker's own traders spot the gap.
That's why the method works best as a process rather than a one-off: small, frequent, consistent returns add up over a month.
What are the real risks?
A lock locks in a return at the prices shown. Things can still go wrong between seeing a lock and placing every bet, so it's worth knowing the main risks and how to handle each one.
- Prices move. If a price shortens before you place the second leg, the return shrinks or turns negative. Place legs quickly and check each price on the bet slip before confirming.
- Stake limits. A bookmaker may accept only part of your stake. Size the remaining legs to match what was actually accepted.
- Voided bets. Bookmakers can void a bet placed at an obvious pricing error under their terms, which can leave you with one side open. Keep an eye out for prices that look far out of line.
- Account restrictions. Bookmakers can limit accounts that consistently take their best prices. Spreading activity across several licensed bookmakers helps.
- Human error. Backing the wrong player or typing the wrong stake is the most common way to lose on a lock. Slow down on the last click.
None of these risks go away completely, but each one can be managed with good habits, and a clear alert with the exact stakes removes a lot of room for mistakes.
How to find locks fast
You can find locks by hand by comparing prices across bookmaker sites, but with thousands of markets moving every few seconds, manual searching finds very few before they close.
Most serious arbitrage bettors use software that:
- watches prices across many Australian bookmakers at once
- checks every combination for a gap
- sends an alert the moment a lock appears, with the bookmaker, the price and the stake for each outcome
When comparing tools, look at how many bookmakers they cover, how fresh the prices are (seconds matter), whether alerts reach your phone instantly, and whether they show exact stakes rather than just a percentage.
AUOdds does this for Australian bookmakers. It watches about 15,000 prices at any moment, re-checks each lock before sending it, and sends every lock to Telegram with the exact split, updating it live if prices move.
Frequently asked questions
Is arbitrage betting legal in Australia?
Yes. Arbitrage betting means placing ordinary bets with bookmakers, which is legal for adults in Australia. Stick to licensed bookmakers: ACMA lists how to check if a gambling operator is legal. Bookmakers can still limit or close accounts under their own terms.
How much money do I need to start arbitrage betting?
You can start with a few hundred dollars, but because returns are a few per cent of the total staked, a larger bankroll spread across several bookmakers makes each lock worth more. Only use money you can afford to have tied up in accounts.
Do bookmakers ban arbitrage bettors?
Bookmakers can limit or close accounts that regularly take their best prices, and that's within their terms. Many arbitrage bettors keep accounts active for longer by spreading their bets across several licensed bookmakers and avoiding unusual stake sizes.
Are arbitrage betting winnings taxed in Australia?
For most recreational punters, gambling winnings aren't treated as assessable income. The ATO's ruling IT 2655 explains the position, which can differ if you're carrying on a business of betting. If you're unsure, ask a registered tax agent.
What's a good arbitrage percentage?
Most locks sit between about 1% and 4% of the total staked. Anything much higher is worth a second look, because a price that far out of line can be an error that a bookmaker may void.
Sources
- Check if a gambling operator is legal, Australian Communications and Media Authority
- 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.