A surebet is the simplest positive-expected-value bet in sports betting: a combination of wagers placed across multiple bookmakers that guarantees a profit no matter what happens in the event. Also called an arbitrage bet, an arb, or a sure bet, it's the closest thing to risk-free betting that actually exists in the Australian bookmaker market.
This guide covers what a surebet is, how surebets work mathematically, how to find them at Australian bookmakers, how much they can make, and the constraints that matter in practice. If you're looking for the longer strategy deep-dive, the full arbitrage guidecovers account management and advanced execution. This piece is the beginner-level introduction.
What is a surebet, exactly?
A surebet is a mathematical situation where the best available prices for every possible outcome of an event, combined across different bookmakers, produce a combined implied probability of less than 100%. The gap between the combined implied probability and 100% is the arbitrage margin — the guaranteed profit as a percentage of total stake.
Every decimal price has an implied probability: 1 divided by the odds. A $2.00 price implies 50%. A $2.10 price implies 47.6%. A $1.90 price implies 52.6%. When you combine the implied probabilities of covering every outcome, the total tells you the book percentage:
- Below 100%: an arbitrage opportunity (surebet).
- Exactly 100%: a mathematically fair market (never seen in practice).
- Above 100%: a normal bookmaker market with margin built in.
A two-way surebet example
Consider an NRL match with the following best prices across Australian bookmakers:
- Penrith Panthers to win: $2.10 at Bet365
- South Sydney Rabbitohs to win: $2.05 at Sportsbet
Implied probabilities: 1/2.10 = 47.62% and 1/2.05 = 48.78%. Combined: 96.40%. The gap from 100% is 3.60% — that's the arb margin.
On a $1,000 combined stake you'd lock in about $36 profit regardless of who wins. The stakes have to be split correctly across the two legs so the return is identical either way: about $494 on Penrith and $506 on South Sydney produces roughly $1,036 of total return on either outcome.
A three-way surebet example (soccer)
Soccer markets have three outcomes (home, away, draw) instead of two, so three-way surebets require prices on all three sides. For example:
- Manchester City to win: $2.40 at Ladbrokes
- Draw: $3.60 at Neds
- Arsenal to win: $3.40 at Bet365
Implied probabilities: 41.67% + 27.78% + 29.41% = 98.86%. Book percentage 98.86% means a 1.14% arbitrage margin. Smaller than a typical two-way arb but still a guaranteed profit across the three-way split.
How to calculate surebet stakes
Staking the same amount on each side of a surebet doesn't work — you have to size each leg so the return is identical regardless of outcome. The formula for the first leg of a two-way surebet:
Stake1 = (Total Stake × Implied Probability1) / Book Percentage
In the Penrith/Souths example above with a $1,000 total stake:
- Stake on Penrith at Bet365: $1,000 × 0.4762 / 0.9640 = $494.00
- Stake on Souths at Sportsbet: $1,000 × 0.4878 / 0.9640 = $506.00
- Payout if Penrith wins: $494 × $2.10 = $1,037
- Payout if Souths win: $506 × $2.05 = $1,037
- Guaranteed profit: $37 on $1,000 combined stake (3.7% margin)
In practice nobody calculates this by hand. The Krok Odds Surebets scanner calculates surebet stakes to the cent, accounting for minimum-stake rounding at individual bookmakers and the practical constraint that you should round your actual placed stakes to reduce account-flagging risk.
Are surebets legal in Australia?
Yes. Unambiguously. Placing surebets at Australian-licensed bookmakers is entirely legal under Australian law. You are placing lawful bets at bookmakers who are free to accept or decline bets at their discretion. No regulator anywhere in Australia treats consistent winning as a criminal matter.
The operational constraint isn't legal — it's commercial. Australian bookmakers reserve the right in their terms of service to restrict any customer for any reason, and they use this right actively against customers they identify as arbers. The gubbing guidecovers the tactics that extend AU bookmaker account longevity.
Are surebets actually risk-free?
Mathematically, once both legs of a surebet are placed at the calculated prices, the profit is guaranteed. In that narrow sense, yes.
Operationally, surebets carry several practical risks:
- Palpable error voids. AU bookmaker terms allow voiding bets placed on prices the bookmaker later determines were displayed in error. If one leg of your surebet is voided, your other leg becomes an unhedged position.
- Stake limits. The bookmaker offering the best price on one side may cap your stake below what the surebet structure requires, preventing you from fully placing the arb.
- Market suspension. One leg can be accepted, then the opposing market can suspend or move before you can place the second leg.
- Account restrictions mid-execution. An account can be restricted between placing leg one and leg two, leaving you with unhedged exposure.
The gubbing stories piece documents specific cases where these operational risks turned supposedly risk-free surebets into losses. The expected-value maths is correct. The real-world execution has friction that matters.
How much can you make from surebets?
Individual surebet margins at Australian bookmakers typically range from 1% to 3%. Occasional larger arbs (4%+) exist but are usually either fleeting or connected to palpable-error situations that get voided.
Realistic retail-scale AU surebet operations produce annual returns in the range of 40-150% of working bankroll, depending on the size of the operation, the number of bookmaker accounts available, and how aggressively accounts get restricted. On a $5,000 starting bankroll, expect $2,000-$8,000 in year-one profit with serious effort and discipline.
The ceiling is imposed by bookmaker account limiting, not by surebet availability. See the six-months arbing piece for an honest breakdown of what year-one actually looks like in terms of dollars, hours, and accounts restricted.
How to find surebets at AU bookmakers
The three approaches:
Manual watching. Open the same market at every AU bookmaker and compare. Works for one-off surebet identification, totally impractical as an ongoing strategy. AU bookmakers have around 300-600 markets active on any given day, across 100+ books.
Generic surebet scanners. Overseas-built scanners that include AU bookmakers as a secondary market. Coverage is usually incomplete (missing BlueBet, Dabble, Neds, TABtouch) and the prices refresh too slowly to catch short-lived arbs.
AU-focused surebet scanners. Tools built specifically for the Australian market, monitoring all major AU bookmakers in real time. The Krok Odds Surebets scanner falls in this category — continuous price comparison across Sportsbet, TAB, Bet365, Ladbrokes, Neds, PointsBet, BlueBet, BetRight, Unibet, TABtouch, Dabble and Betfair Exchange, with real-time surebet alerts.
Surebets vs value bets (+EV bets)
Surebets and value bets are the two core approaches to positive-expected-value betting. They work differently:
- Surebets guarantee a profit on each placement by covering every outcome. Zero variance per bet. Smaller per-bet profit margins.
- Value bets (also called positive EV bets) are single-sided bets where the offered price exceeds the true probability of the outcome. Real variance per bet. Larger per-bet profit margins on average.
Most serious Australian advantage bettors use both strategies. Surebets for consistent cashflow and guaranteed returns. Value bets for compounding edge over the long term. The year-one retrospectivecovers how this mix evolves in practice.
Frequently asked questions about surebets
Is arbitrage betting legal in Australia?
Yes. Placing arbitrage bets at Australian-licensed bookmakers is entirely legal. Bookmakers retain the right to restrict customer accounts as they choose.
Do bookmakers ban surebet customers?
Yes, in practice almost every AU corporate bookmaker restricts accounts of customers they identify as surebet arbers. The restrictions typically limit max stakes rather than closing the account outright. The gubbing guidecovers techniques that extend account life.
How much do you need to start surebet betting?
A working bankroll of $3,000-$5,000 across 10-12 bookmaker accounts is a practical starting point. The capital needs to be distributed across multiple books because every surebet requires placing legs at different bookmakers simultaneously.
Can you make a living from surebets in Australia?
No, realistically. AU bookmaker account limits cap the practical scale of surebet operations. Annual profits of $15,000-$50,000 are achievable for serious operators but require substantial time investment and constant account rotation. Surebets are better thought of as a meaningful side income than as a career replacement.
What's the best surebet scanner for Australian bookmakers?
The best AU surebet scanner is one that covers all major Australian bookmakers (not just the top 3-4), refreshes prices fast enough to catch short-lived arbs, and calculates stakes to account for rounding. The Krok Odds Surebets tool is built specifically for AU markets and covers 100+ bookmakers in real time.
Daniel writes about the maths underneath advantage betting — expected value, Kelly sizing, closing line value, bankroll theory. Translates the theoretical side into practical decisions AU punters can actually apply.