Best Surebet: How to Rank Locks by Margin, Stakes and Timing
- The margin shows the return per dollar at the prices shown, but stake capacity decides how many dollars you actually make.
- A 1.5% AFL head-to-head lock filled at A$1,000 can return about three times more than a 4% table tennis lock capped at A$60 on one leg.
- Voids, mismatched settlement rules and likely price errors can turn a big-margin lock into an ordinary open bet.
- Time to start affects how calmly you can place both legs and how long your money stays tied up.
- Rank locks with a quick scorecard (dollar return, market quality, settlement match, price sanity and timing) rather than sorting by percentage.
The best surebet is not always the one with the biggest percentage. A 4% lock looks better than a 1.5% lock on a list. But the number on the alert ignores three things that decide what you actually keep: how much you can stake, how likely a leg is to be voided, and how long until the event starts. AUOdds data shows the typical lock over the last 30 days sat around 1.4%, across 3,750 locks at nine Australian bookmakers. Most of your decisions will be between small margins. This guide shows how to rank them, with worked A$ examples, a quick scorecard and an honest look at the risks.
- What makes the best surebet more than the biggest percentage?
- How does stake capacity change the dollar return?
- Why do voids and settlement rules shrink a big margin?
- How does time to start affect which lock you take?
- How do you rank the best sure bets today in under a minute?
- What should you check before placing any lock?
What makes the best surebet more than the biggest percentage?
A lock, or surebet, exists when the best prices across different bookmakers cover every outcome for less than 100% in combined implied probability. The margin tells you the return per dollar at the prices shown. It does not tell you how many dollars you can put through, or what happens if something goes wrong.
Think of every lock as having four numbers, not one:
- Margin: the return at the prices shown, for example 1.5%.
- Stake capacity: the most you can realistically get on each leg before a bookmaker limits or rejects the bet.
- Settlement risk: how likely a leg is to be voided, re-priced or settled under different rules from the other leg.
- Time to start: how long you have to place both legs, and how long your money sits tied up until results.
Multiply the margin by your capacity to get the dollar return. Settlement risk and time to start then decide how much of that return is reliable.
This is why lists of the 'best surebet today' sorted by percentage can mislead. Big margins often appear where prices are set less carefully, such as niche sports, lower-tier leagues and obscure player markets. Those same markets tend to carry lower stake limits and more unusual settlement rules. A smaller margin on a heavily traded market, such as an AFL or NRL head-to-head, often comes with higher limits and simple, consistent settlement.
None of this makes a high margin bad. The percentage is where the assessment starts, not where it finishes. The sections below put real-looking numbers on each factor. That way you can compare locks the way you would compare any other use of your money.
How does stake capacity change the dollar return?
Here is the comparison that the percentage alone hides. Both examples use decimal odds and pre-match bets only.
Lock A: AFL head-to-head, about 1.5%
- Team A at 1.95 with one bookmaker, Team B at 2.12 with another.
- Implied probabilities: 51.28% + 47.17% = 98.45%.
- With A$1,000 total: A$520.88 on Team A, A$479.12 on Team B.
- Either result returns about A$1,015.72. That is a return of about A$15.72 (1.57%) at the prices shown.
Major-league head-to-head markets often accept stakes of this size, though every account is different.
Lock B: table tennis, about 4%
- Player A at 2.30, Player B at 1.90.
- Implied probabilities: 43.48% + 52.63% = 96.11%, a margin of about 4.05%.
- Suppose the bookmaker offering 2.30 accepts only A$60 on this market.
- That caps the lock at A$60 on Player A and A$72.63 on Player B, A$132.63 in total.
- Either result returns about A$138.00, a return of about A$5.37.
The table tennis lock has nearly three times the margin and roughly a third of the dollar return. To match Lock A, you would need to find and place about three locks like Lock B. Each one carries its own chance of a mistake or a moved price.
The A$60 limit is an example, not a published rule. Your own limits depend on the bookmaker, the market and your account history, and they can tighten over time. Before you calculate, note the realistic maximum on the tightest leg. The smallest limit sets the size of the whole lock.
Why do voids and settlement rules shrink a big margin?
A lock only returns what it shows if both legs settle on the same result. If one leg is voided and the other stands, you are left holding an ordinary single bet. You might win it or lose it, but it is no longer a lock.
Common reasons a leg can be voided or settled differently include:
- Obvious price errors. A price far out of line with the market may be cancelled under a bookmaker's terms.
- Retirements and abandonments. In sports like tennis and table tennis, bookmakers may settle a retired or unfinished match differently. One leg can stand while the other is voided.
- Market definitions. One book may settle a line or total including extra time, while another may not. Two prices can look like opposite sides while covering different things.
- Late changes. Changed venues, start times or players can trigger voids under some terms.
Always read the settlement rules of both bookmakers for that sport. Don't assume they match.
Now put the risk into the Lock B numbers. Say the A$60 leg is voided and refunded, and the A$72.63 leg stands at 1.90. You either collect about A$65 profit or lose A$72.63. A loss that size wipes out the profit from more than a dozen A$5 locks.
Big margins are also more likely to be errors. A 4% gap on a lightly traded market often exists because one price is stale or mistaken, and those are exactly the prices that get corrected or cancelled. A 1.5% gap between two sharp prices on an AFL match is less likely to be challenged. When you rank locks, discount the margin on any leg that looks too good to be true.
How does time to start affect which lock you take?
Time to start cuts both ways, so it helps to split it into three effects.
Placement window. You need time to open two accounts, check prices and enter stakes. AUOdds data puts typical price age at about 10 seconds, but prices can still move between the alert and your second bet. A lock with five minutes to start leaves little room to fix a mistake, and some markets suspend near the start. Online in-play sports betting isn't offered to Australians, so if you miss the window before the start, the lock is gone.
Capital tied up. Money in a lock is unavailable until the event settles. A Thursday lock on a Sunday AFL match holds your funds for three days. A table tennis match starting in 20 minutes frees them within the hour. Faster turnover matters if your bankroll is small, and far less if your funds would sit idle anyway.
Exposure to change. A longer gap before the start leaves more time for team changes, venue moves or weather. Any of these might trigger a void under one book's rules but not the other's.
One simple way to weigh this is return per day of capital. Lock A returns about A$15.72 on A$1,000 over three days. Lock B returns about A$5.37 on A$132.63 within an hour. On paper, Lock B turns over faster. But you can only repeat it if more locks with similar limits keep appearing, and each repeat adds placement and void risk.
A sensible personal rule is to favour locks that give you at least 15 to 30 minutes to place both legs calmly, on events that settle within a day or two.
How do you rank the best sure bets today in under a minute?
When several alerts land at once, use a quick scorecard instead of sorting by percentage. Work through it in this order:
- Dollar return at a realistic stake. Multiply the margin by the stake your tightest leg will accept. This is the headline number.
- Market quality. Major leagues and main markets (head-to-head, line, totals) score higher than niche sports and props.
- Settlement match. Check that both legs use the same rules for retirements, extra time and abandonment. If not, skip or discount heavily.
- Price sanity. If one price is far from every other bookmaker, treat it as a possible error.
- Time to start. Make sure there is enough time to place both legs without rushing, and that settlement is soon enough for your bankroll.
Here is how three locks might compare:
- AFL head-to-head, 1.5%, A$1,000 capacity, starts in two hours: about A$15 return, clean settlement. Take first.
- NRL line, 2.1%, A$400 capacity, starts in four minutes: about A$8 return, high placement risk. Probably skip.
- Table tennis, 4.0%, A$130 capacity, retirement rules differ: about A$5 return, open-bet risk. Skip.
Margins this small are normal. AUOdds data shows 889 locks in the last seven days, with about 15,000 prices tracked at any moment. With that many options, you rarely need to accept a messy one. The best surebet today is usually the cleanest lock you can fill comfortably, not the biggest number on the screen.
What should you check before placing any lock?
Even a well-ranked lock can go wrong through simple mistakes. A short routine before placing catches most of them.
- Licensed bookmakers only. Use bookmakers licensed in Australia. ACMA explains how to check whether a gambling operator is legal.
- Same event, same market. Confirm the teams, date, market type and whether extra time counts.
- Fresh prices. Re-check both prices just before placing. If one has moved, recalculate before you place the other leg.
- Tightest leg first. Place the leg most likely to be limited or to move first, so a rejection doesn't leave you exposed.
- Record everything. Note stakes, prices and bet IDs so you can query a settlement and track your results.
Be honest about the real risks. Prices move between the alert and your bet, stakes get limited, bets can be voided and typing errors happen. A lock locks in a return at the prices shown, provided both legs are accepted and settle as expected. If you are unsure how winnings are treated for tax, start with the ATO's guidance on gambling winnings.
A reminder on gambling responsibly. Betting is for adults aged 18 and over. Set a budget you are comfortable losing, and stop if betting no longer feels like a controlled hobby. BetStop, the National Self-Exclusion Register, lets you exclude yourself from licensed Australian online and phone bookmakers. Gambling Help Online offers free, confidential support 24/7.
Frequently asked questions
Is a higher-percentage surebet always better?
No. The percentage is the return per dollar at the prices shown. If the tightest leg only accepts a small stake, a high-margin lock can return fewer dollars than a lower-margin lock with room to stake. Big margins on niche markets also carry more risk of voids and price corrections. Compare the dollar return at a realistic stake first.
Can I take a lock after the match has started?
No. Online in-play sports betting isn't offered to Australians, so both legs need to be placed before the event starts. That is why time to start matters when ranking locks. If an alert arrives only a few minutes before the start, you may not have time to place and check both legs. Skipping it is often the sensible choice.
Should I avoid locks on niche sports entirely?
Not necessarily, but treat them with care. Check the realistic stake limit on each leg, read both bookmakers' rules for retirements and abandoned matches, and ask whether one price looks like an error. If the settlement rules differ or the dollar return is tiny, a cleaner lock on a major league is usually the better use of your time and funds.
Are surebet winnings taxed in Australia?
The ATO's Taxation Ruling IT 2655 deals with gambling and betting winnings, and the ATO also publishes guidance on gambling winnings. Whether your winnings are assessable depends on your circumstances, including whether your betting amounts to carrying on a business. Read the ATO material and speak to a registered tax professional if you are unsure how it applies to you.
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
- Crypto asset prizes and gambling winnings, Australian Taxation Office
- 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.