Arbitrage Betting Calculator 2 Way: NRL, AFL and Tennis Stakes Worked Out
- A 2-way lock exists when 1 ÷ odds on each side adds up to less than 1.00, and each stake is the total stake times that side's share.
- AFL and NRL head-to-head matches can end in a draw, so both legs must handle a draw the same way or the lock can break.
- Tennis retirement rules are not uniform across bookmakers, so match the rules on both legs before staking.
- Round stakes carefully and recalculate from any limited leg, because typical locks are only around 1.5%.
- A lock only locks in a return at the prices shown: prices move, stakes get limited, bets can be voided and mistakes happen.
An arbitrage betting calculator 2 way splits one total stake across two head-to-head prices so the return is close to identical whichever side wins. It is the simplest arb maths there is. But NRL, AFL and tennis each carry a settlement quirk that can quietly break a lock: a drawn footy match, or a tennis player retiring hurt. AUOdds data shows 3,048 locks across 9 Australian bookmakers in the last 30 days, with a typical lock around 1.5%. Margins that thin leave no room for a rules mismatch, which can wipe out weeks of small returns. This guide walks through the stake maths with real-looking odds. It then covers the code-specific rules to check before you place either leg.
- How does an arbitrage betting calculator 2 way work out each stake?
- Why can a draw break an AFL or NRL head-to-head lock?
- How do tennis retirement rules affect a 2-way arb?
- What should you check in an arbitrage calculator in Australia?
- How do you round stakes without losing a thin lock?
- What are the real risks with a 2-way lock?
How does an arbitrage betting calculator 2 way work out each stake?
A 2-way market has two outcomes: Team A or Team B, Player 1 or Player 2. A lock exists when the best price on each side, usually at different bookmakers, adds up to less than 100% in implied probability.
This is the maths every betting arbitrage calculator uses:
- Implied % for each side = 1 ÷ decimal odds
- Add them together. A total under 1.00 (100%) means a lock at the prices shown
- Stake on each side = total stake × that side's implied % ÷ the total
- Return = total stake ÷ the total
Worked example: NRL head-to-head
Bookmaker A has the Storm at 2.10. Bookmaker B has the Panthers at 2.00.
- 1 ÷ 2.10 = 0.4762
- 1 ÷ 2.00 = 0.5000
- Total = 0.9762, so the market sums to 97.62%
With $500 in total:
- Storm stake: $500 × 0.4762 ÷ 0.9762 = $243.90
- Panthers stake: $500 × 0.5000 ÷ 0.9762 = $256.10
If the Storm win, the return is $243.90 × 2.10 = $512.19. If the Panthers win, it is $256.10 × 2.00 = $512.20. Either way you get back about $512, which is roughly $12, or 2.4%, on $500 outlaid.
That is the whole job of an arb betting calculator: it turns two prices into two stakes. It cannot tell you whether the two markets settle the same way. That is where NRL, AFL and tennis need extra care.
Why can a draw break an AFL or NRL head-to-head lock?
Football codes are not truly two-outcome sports. AFL regular-season matches can finish level after four quarters. NRL regular-season games can still end in a draw if golden point extra time produces no winner. Draws are uncommon, but a 2-way calculator assumes they cannot happen.
How a draw is treated depends on the market you bet into, and terms are not uniform across bookmakers or market types. A head-to-head market might list the draw as a third selection, apply dead-heat rules or refund stakes. It might also settle another way set out in that bookmaker's rules. The only reliable answer is the published market rules on the day.
The problem arises when your two legs use different treatments. Take an AFL lock at 1.80 and 2.30. The implied total is 0.5556 + 0.4348 = 0.9903, about a 1% lock. On $1,000 you would stake $560.98 and $439.02 for a return of about $1,009.76.
Now suppose the match is drawn and the two legs settle differently. One is refunded in full and the other is graded a loser. You get $560.98 back and lose $439.02. A lock meant to return about $10 has cost you $439.
To protect a 2-way footy lock:
- Read the draw rule on both markets before placing either leg
- Only pair legs where a draw is handled the same way on both sides
- If a market lists the draw as its own selection, it is really a 3-way market, so use a 3-way calculator instead
- Treat a mismatch as no lock, however good the margin looks
How do tennis retirement rules affect a 2-way arb?
Tennis looks like the cleanest 2-way sport: no draws, two players, one winner. The catch is retirement. If a player pulls out injured mid-match, each bookmaker settles bets under its own retirement rule, and those rules are not the same everywhere.
In broad terms, a retirement rule decides whether bets stand or are voided. That can hinge on how much of the match has been played, or on whether the match has to be completed at all. Some rules also deal with a walkover before the first ball. Check the exact wording at each bookmaker rather than relying on what seems typical.
Worked example: tennis with mismatched rules
Bookmaker A has Player 1 at 1.55. Bookmaker B has Player 2 at 2.95. The implied total is 0.6452 + 0.3390 = 0.9842, about a 1.6% lock. On $300 you would stake $196.67 on Player 1 and $103.33 on Player 2, returning about $304.83 either way.
Now say Player 2 retires early in the second set. Bookmaker A's rule lets the bet stand, so Player 1 is paid as the winner: $304.84. Bookmaker B's rule voids the match, so your $103.33 comes back. You finish ahead, but the result was decided by fine print, not by the calculator.
Flip it around so Player 1 retires instead. The leg that stands is now graded a loser while the other is voided, and you lose the $196.67 stake.
Retirements are common enough in tennis to justify a minute of checking before every tennis lock. Match the retirement rules on both legs, or skip the lock.
What should you check in an arbitrage calculator in Australia?
Any arbitrage calculator in Australia should accept decimal odds, which is how local bookmakers display prices. Beyond the maths, run through this list before staking:
- Licensed books only. Both bookmakers should be licensed Australian operators. ACMA explains how to check whether a gambling operator is legal [ACMA-LEGAL].
- Same event, same market. Confirm the match, the date and the market name. Two markets with similar names can carry different terms.
- Draw and retirement rules matched. As covered above, this is the most common way a 2-way lock breaks on Australian codes.
- Price freshness. Prices move, and a quote that was right a minute ago may be gone. AUOdds prices are typically about 10 seconds old, but confirm every price on the bookmaker's own betslip.
- Maximum stake. If one leg is limited below your calculated stake, recalculate both legs at the lower figure.
- Pre-match only. Online in-play sports betting is not offered to Australians, so every lock here is placed before the start.
- Your total stake. Pick an amount you can afford to leave tied up until both legs settle.
A good arb betting calculator also shows the return on each side. That lets you see straight away whether the two numbers line up within a few cents. If they don't, recheck the odds you entered before you place anything.
Keep a simple record of each lock: the event, both prices, both stakes and the rules you checked. It takes seconds and makes any settlement dispute far easier to sort out.
How do you round stakes without losing a thin lock?
Calculators return stakes to the cent, but many people prefer round figures. With a typical lock around 1.5%, rounding has to be done carefully.
Go back to the NRL example: $243.90 at 2.10 and $256.10 at 2.00.
- Rounded to $244 and $256: the returns are $512.40 and $512.00. It is still a lock, at about $12 either way.
- Rounded to $250 and $250: the returns are $525.00 and $500.00. One outcome now only breaks even, so the lock is gone.
A simple rule: round to the nearest dollar, then check both returns are above your total outlay. If either one is not, adjust.
When a stake gets limited
Say Bookmaker A will only accept $150 on the Storm. Work back from the limited leg:
- Return target = $150 × 2.10 = $315
- Panthers stake = $315 ÷ 2.00 = $157.50
- Total outlay is $307.50 and the return is $315, so about $7.50 is locked in at those prices
Place first the leg most likely to be limited or to move, then place the second leg straight away. If the second price drifts before you get on, rerun the betting arbitrage calculator with the new odds rather than guessing. A drift from 2.00 to 1.95 on the Panthers would push the total to about 0.9890. The lock shrinks but is still there, and the stakes need to change to keep both returns level.
What are the real risks with a 2-way lock?
A 2-way lock locks in a return at the prices shown. It does not remove the practical risks:
- Prices move between seeing a lock and placing the second leg.
- Stakes get limited, sometimes after a run of winning bets.
- Bets can be voided, for example over price errors, abandoned matches or rule-based settlements like those above.
- Mistakes happen, such as backing the wrong team, picking the wrong match or typing a stake with an extra zero.
- Funds sit idle in bookmaker accounts until both legs settle.
Opportunities are not the hard part. AUOdds data counted 1,185 locks in the past 7 days. The discipline is in checking rules, confirming prices and keeping records every time.
On tax, the ATO's long-standing position is that winnings of a recreational punter are generally not assessable income [ATO-IT2655] [ATO-WINNINGS]. If your situation is unusual, get personal advice rather than assuming.
A reminder before you bet
Arbing is still gambling, and you must be 18+ to bet. If betting stops feeling like a controlled hobby, BetStop, the National Self-Exclusion Register, lets you exclude yourself from licensed online and phone bookmakers in Australia [BETSTOP] [ACMA-BETSTOP]. Gambling Help Online offers free, confidential support at any hour [DSS-GAMBLING].
Frequently asked questions
What is the formula behind a 2-way arb calculator?
Divide 1 by each decimal price and add the two results. If the total is below 1.00, the prices form a lock. Each stake equals your total stake multiplied by that side's implied figure, divided by the total. Your return is the total stake divided by the total, so both outcomes pay about the same amount at the prices shown.
Is an AFL or NRL head-to-head always a 2-way market?
Not always. Both codes can produce a draw, and bookmakers may treat it as a separate selection, under dead-heat rules, as a refund or in another way under their terms. If the draw is its own selection, treat the market as 3-way. For a genuine 2-way lock, both legs must settle a draw the same way.
Can a tennis retirement turn a lock into a loss?
Yes, if the two bookmakers apply different retirement rules. One leg might stand and be graded a loser while the other is voided, leaving you down one stake. Read each bookmaker's retirement wording before placing either leg, and skip the lock if the rules do not match on both sides.
Should I round the stakes a calculator gives me?
You can, but check the result. Rounding to the nearest dollar usually keeps a lock intact. Bigger rounding, such as splitting stakes evenly, can leave one outcome at break-even or a loss. After rounding, multiply each stake by its odds and confirm both returns are higher than your total outlay.
Sources
- Check if a gambling operator is legal, Australian Communications and Media Authority
- Taxation Ruling IT 2655: gambling and betting winnings, Australian Taxation Office
- Crypto asset prizes and gambling winnings, Australian Taxation Office
- BetStop, Australian Government
- BetStop: the National Self-Exclusion Register, Australian Communications and Media Authority
- Gambling, Department of Social Services
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.