Arbitrage Betting for Dummies: Your One-Page Australian Cheat Sheet

By the AUOdds team · Updated 31 Oct 2026 · 7 min read

Arbitrage betting for dummies doesn't need to be a long read, so this guide is built as a printable one-page cheat sheet for Australian bookmakers. Each section below becomes one block on the page: the idea, the two formulas, a worked example, a placing checklist, the main risks and the admin. It isn't a step-by-step first-bet tutorial. It's the reference you keep beside you once you know the basics. The figures use plain decimal odds and Australian dollars, and the language is deliberately simple. A lock locks in a return at the prices shown, but prices move, stakes get limited and bets can be voided, so the sheet puts those warnings where you'll see them. Print it, date it and keep it next to your calculator.

Arbitrage betting for dummies: what goes on the one page?

A cheat sheet is not a course. It is the single page you keep beside the keyboard or pin to the fridge, so you don't have to remember everything at the moment a price appears. The aim is to cut decisions down to a few quick checks.

The page is organised into five blocks, and each one maps to a section of this guide:

• The idea: one sentence on what a lock is.
• The maths: two formulas and one example.
• The checklist: what to confirm before and after each leg.
• The warnings: the four things that most often go wrong.
• The admin: records, tax notes and where to get help.

Print it on one A4 sheet in portrait. Use bold for the formulas and leave a blank box at the bottom for your own notes, such as your bankroll limit for the week and which accounts are already restricted.

If you already understand the basics, this page is your quick reference. If you want a slow walk through your first bet, the beginners guide covers that in more detail. The cheat sheet assumes you know how to log in, deposit and find a market, and it focuses only on what to check when time is short.

One more tip: write the date on the sheet. If you change your process, print a fresh copy rather than scribbling over the old one. A tidy page is easier to trust when you are moving quickly, and an outdated note is worse than no note at all.

Arbitrage betting explained simple: what is a lock?

Here is arbitrage betting explained simple enough for one line: when bookmakers disagree on a price, you back every outcome of the same event at different books so the return is the same whichever side wins, and that return is higher than your total outlay.

Australians usually call this a lock. Overseas it is often called an arb or a surebet. The word means the return is locked in at the prices shown, not that nothing can go wrong.

Why does it happen? Bookmakers set their own prices and move them at different speeds. One might shorten a favourite after a team announcement while another is still a few seconds behind. For a brief window, the best available price on each side adds up to less than 100% implied probability.

The quick test for your sheet:

• Convert each decimal price to implied probability: 1 ÷ odds.
• Add them up across every outcome.
• Under 1.00 (100%) is a lock. Over 1.00 is a normal market with the bookmaker's margin built in.

Most locks are small. According to AUOdds data, the typical lock over the last 30 days was about 1.5%, across 3,658 locks found from 9 bookmakers in that period. Small margins are normal, which is why accuracy matters more than speed alone.

One more line for the sheet: online in-play sports betting isn't offered to Australians, so the locks this page deals with are bets placed before the event starts.

Which two formulas belong on the cheat sheet?

You only need two formulas. Write them in bold near the top of the page.

Formula 1: total return = total outlay ÷ (sum of 1/odds)

Formula 2: stake on each outcome = total outlay × (1/odds for that outcome) ÷ (sum of 1/odds)

Everything else is arithmetic.

Worked example (tennis, two outcomes)

Player A is $2.06 at Bookmaker 1. Player B is $2.00 at Bookmaker 2. You plan to outlay $400 in total.

• 1 ÷ 2.06 = 0.4854
• 1 ÷ 2.00 = 0.5000
• Sum = 0.9854, which is under 1, so it is a lock of roughly 1.5%.

Stakes:

• Player A: 400 × 0.4854 ÷ 0.9854 = $197.04
• Player B: 400 × 0.5000 ÷ 0.9854 = $202.96

The return either way is about $405.90, so the lock is worth about $5.90 at these prices.

Rounding matters. If you bet $197 and $203 to keep things tidy, the returns become $405.82 and $406.00. The smaller figure, $405.82, is your real locked return, so you lock in about $5.82. Always check the lower of the two returns after rounding, not the higher.

For three-way markets such as soccer (home, draw, away), the formulas are the same. You just add a third 1/odds term to the sum. Keep a calculator or spreadsheet open rather than doing this in your head, because a slip on one digit can turn a small lock into a loss.

What should you check before and after each leg?

This is the part of the sheet you will use most. Tick each line every time, even when you feel confident.

Before placing anything

• Is it the same event, same market and same line at both bookmakers? Markets with similar names don't always settle the same way.
• Are both prices still live? Prices move constantly, so refresh before you commit.
• Have you read how each bookmaker settles this market, including what happens if a player retires or a game is abandoned?
• Do you have enough funds in both accounts?
• Is each bookmaker licensed in Australia? ACMA explains how to check whether a gambling operator is legal.

Placing the legs

• Place the leg most likely to move or be limited first, usually the bigger or less common price.
• Confirm the bet slip shows the exact stake and price you calculated.
• If the first leg is accepted at a lower price or a reduced stake, recalculate before placing the second.

After placing

• Screenshot both bet confirmations.
• Record the event, prices, stakes and expected return.
• Check both bets show in your account history.

If something goes wrong between legs, don't chase. Recalculate with the prices actually available and decide calmly whether to cover the position or accept a small loss. A clear head beats a fast click every time.

What risks should the cheat sheet warn you about?

Put this box in a different colour so it stands out. A lock only holds if both bets stand at the prices you calculated.

1. Prices move. Prices can update within seconds. AUOdds tracks about 15,000 prices at any moment, with price age around 10 seconds, which is quick, but no feed is instant and the bookmaker's own price on the bet slip is the one that counts.

2. Stakes get limited. Bookmakers can restrict how much you bet, and accounts that regularly take the best price may be limited over time. Plan for the possibility that a second leg won't accept your full stake.

3. Bets can be voided. Obvious pricing errors, rule differences or abandoned events can lead to one leg being cancelled while the other stands. That leaves you with an open bet rather than a lock.

4. Mistakes happen. Wrong market, wrong player, a typo in the stake, a decimal point in the wrong place. These are the most common problems and the most avoidable.

A simple habit helps: before you click confirm on the second leg, read the slip aloud. It sounds silly, but it catches errors.

Also keep your expectations realistic. With typical locks around 1.5%, one bad mistake can wipe out the return from many good ones. Treat the sheet as a way to reduce errors, not as a promise of results.

How do you handle records, tax and wellbeing on the same page?

The bottom of the sheet covers admin. It is the dull part, but it is where good habits live.

Records

Keep a simple log with the date, event, bookmakers, prices, stakes, expected return and actual result. Review it weekly. You'll quickly recognise patterns, such as which markets cause the most price changes or which accounts have been limited.

Tax

The ATO's guidance on gambling winnings is the place to start, and Taxation Ruling IT 2655 sets out the factors used to decide whether betting activity could be treated as carrying on a business. For most people betting as a hobby, winnings generally aren't treated as income. If your betting becomes regular, organised and large scale, get advice from a registered tax agent rather than assuming.

Wellbeing

Write these lines at the very bottom of your sheet:

• 18+ only.
• Set a weekly limit and stick to it.
• Locks are still gambling: money is at stake on every bet.
• BetStop, the National Self-Exclusion Register, lets you exclude yourself from licensed online and phone betting providers in Australia.
• Gambling Help Online offers free, confidential support.
• The Department of Social Services also publishes information on gambling and where to find help.

If betting stops feeling like a controlled hobby, take a break. That is a good decision, not a failure.

Frequently asked questions

Sources

1. Check if a gambling operator is legal, Australian Communications and Media Authority
2. Taxation Ruling IT 2655: gambling and betting winnings, Australian Taxation Office
3. Crypto asset prizes and gambling winnings, Australian Taxation Office
4. BetStop: the National Self-Exclusion Register, Australian Communications and Media Authority
5. BetStop, Australian Government
6. Gambling, Department of Social Services

More guides

• What Is Arbitrage Betting in Tennis? AU Retirement Rules
• Arbitrage Betting Guide: Splitting a Bankroll Across 9 Books
• Surebet Review: We Score AUOdds Against Our Own Checklist
• Horse Racing Dutch Betting Calculator: Scratchings Fixes

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.