Guide · 7 min read
Arbitrage calculator: split your stakes and work out the arb percentage
Enter the odds, choose a total stake and you're done: the calculator splits your money across two or three outcomes, shows the margin and, if you want, prices in Austria's betting fee and rounded stakes. The formula sits underneath so you can check every result yourself.
Updated 22 October 2026
Contents
The arbitrage calculator
Enter the decimal odds exactly as they appear on the bet slips; a comma or a full stop both work as the decimal mark. The example values show a typical sure bet: 2.06 at Bookmaker A and 2.00 at Bookmaker B. On €1,000 that is €492.61 and €507.39, and either outcome pays €1,014.78, about €14.78 more.
How the calculator works
The calculator answers two questions. Is this combination of odds a sure bet at all? And how much do you stake where, so that every outcome pays out about the same?
- 2 or 3 outcomes. Two outcomes fit tennis, basketball including overtime, over/under lines and handicaps without a draw. Three outcomes are for football 1X2 or ice hockey after regulation time. The guide to three-way arbitrage covers those in depth.
- Total stake. This is the sum of all stakes, not the stake per bookmaker. The calculator splits it in proportion to the odds.
- Result. For each outcome you see the stake, the payout if it wins and the result after the total stake is taken off. Above the table are the sum S, the margin and the return.
It uses the same stake logic as the calculator in the ArbVantage app. What it cannot know: whether the odds are still available when you bet, whether the bookmaker accepts your full stake, and whether both bets are settled under the same rules. Those you check yourself before betting; the guide to arbitrage betting risks goes through each one.
The formula: working it out by hand
Every decimal price stands for an implied probability of 1/odds. Add these up for the best price on each outcome:
S = 1/odds₁ + 1/odds₂ (+ 1/odds₃)
S < 1 → sure bet
You get the stake on each outcome by splitting the total stake in proportion to those reciprocals:
stakeᵢ = total × (1/oddsᵢ) / S
payout (whichever outcome wins) = total / S
S = 1/2.10 + 1/2.05 = 0.47619 + 0.48780 = 0.96400. That is below 1.
Stake A = 1,000 × 0.47619 / 0.96400 = €493.98. Stake B = 1,000 × 0.48780 / 0.96400 = €506.02. Either outcome pays about €1,037.35, roughly €37 more than the total stake. That is before any fees, and only if both bets are accepted at these odds and stand.
A deliberately large example, so the numbers are easy to read. Typical sure bets are 1–2%, many below 1%, like the 2.06 / 2.00 the calculator starts with. From about 8%, a margin is usually a pricing error a bookmaker will void.
The same formula works for three outcomes; you just add a third term. Why bookmakers' prices drift apart enough for S to drop below 1 is explained in sure betting explained.
Reading the arb percentage and the margin
"A 2% arb" can mean two different things, and calculators online often mix them up:
margin as % of payout = (1 − S) × 100
return on total stake % = (1/S − 1) × 100
In the example that is 3.60% of the payout, or a 3.73% return on the stake. With small margins the two numbers sit close together: S = 0.98 gives 2.00% and 2.04%. The ArbVantage app shows the return on the total stake, because you can use it directly: €500 staked at 1.5% is about €7.50 if everything goes through.
For context, most pre-match sure bets sit between 1% and 2%. Values well above that are often a stale price, a bookmaker error or two markets with different settlement rules. Check those twice before you put any money down. Which margins are worth the effort is covered in what is a good arbitrage percentage?
Spreading the profit evenly or putting it on one outcome
By default the calculator splits the stakes so that every outcome pays the same. You can also put the whole surplus on one outcome. You then stake just enough on the other outcomes to get the total stake back, and the rest goes on your chosen side:
stakeⱼ = total / oddsⱼ (for every other outcome j)
profit if outcome k wins = total × oddsₖ × (1 − S)
With €1,000 and odds of 2.10 / 2.05, you stake €487.81 on outcome 2 (1,000 / 2.05, rounded up to the cent) and €512.19 on outcome 1. If outcome 1 wins, it pays €1,075.60, about +€75.60. If outcome 2 wins, you get €1,000.01 back, practically ±€0.
Mathematically this is not a better bet, only a different split: you swap a small plus on every outcome for a bigger plus on one outcome and nothing on the other. It can make sense when one side is clearing a bonus wagering requirement (see converting free bets), or when you deliberately want more turnover at one bookmaker.
Calculating with Austria's 5% betting fee
Since 1 April 2025 Austria has charged a 5% betting fee (Wettgebühr) on the stake. The bookmaker owes it, and most bookmakers absorb it. Some pass it on. For Interwetten, our bookmaker research indicates that the fee is taken from the payout of winning bets for Austrian customers (as of October 2026; check your own bet slip). The background is in our guide to Austria's betting tax.
To include it, tick "5% betting fee taken from the payout" on the outcome concerned. The calculator then uses the effective odds:
effective odds = odds × 0.95 (fee taken from the payout)
effective odds = odds / 1.05 (fee charged on top of the stake)
2.10 becomes 2.10 × 0.95 = 1.995. S = 1/1.995 + 1/2.05 = 0.98906, and the return falls from 3.73% to 1.11%. On €1,000 you stake €506.80 and €493.20, and both outcomes pay about €1,011.06: roughly +€11 instead of +€37.
On a typical 1.5% sure bet, a 5% deduction on one side is enough to turn it negative. If a bookmaker charges the fee on top of the stake, enter the odds divided by 1.05 and leave the box unticked. The same logic applies to Germany's 5.3% sports betting tax where a bookmaker passes it on: enter the odds multiplied by 0.947. Our guide to tax and legality covers the German rules.
Rounding stakes and what it costs
€493.98 looks unusual on a bet slip and is fiddly to type. Rounded stakes are more practical, but they shift the payouts:
| Rounding | Stake A (2.10) | Stake B (2.05) | Total | Worst outcome |
|---|---|---|---|---|
| To the cent | €493.98 | €506.02 | €1,000 | +€37.34 |
| Light | €494 | €505 | €999 | +€36.25 |
| Natural | €495 | €510 | €1,005 | +€34.50 |
| Heavy | €490 | €500 | €990 | +€35.00 |
The rounding step depends on the size of the stake: from €500, "natural" rounds to €10; below that, to €5 or €1. That is why the total can end up slightly different from the amount you entered. If rounding would cost more than about a third of the margin, the calculator falls back to a finer step and tells you so.
At a 3.7% margin this barely matters. On a 0.7% sure bet, heavy rounding can use up the whole edge. Rule of thumb: the smaller the margin, the finer you round.
Assumptions for all examples: decimal odds, both bets accepted in full at the odds shown and not voided, no limits, amounts rounded to the cent.
In the app, ArbVantage looks for these price differences between bookmakers for you, prices in known betting fees for your country and fills in this calculation automatically. You can try it free for 14 days.
Frequently asked questions
How do I calculate a sure bet without a calculator?
Work out 1/odds for each outcome and add the values up. If the sum S is below 1, it is a sure bet. The stake on each outcome is total stake × (1/odds) / S.
What does "a 2% arb" mean?
Usually the return on the total stake: on €1,000 about €20 is left over, if every bet is accepted at those odds and stands. Some sites mean the margin as a share of the payout instead, which is slightly smaller.
Does the calculator work with a betting fee?
Yes. Tick the 5% betting fee on an outcome and the calculator uses the odds after the fee is taken from the payout. If a bookmaker charges the fee on top of the stake, enter the odds divided by 1.05 instead.
Can I put all the profit on one outcome?
Yes. Choose "All on outcome …". The other outcomes then return roughly your total stake, and the whole surplus only comes in if your chosen outcome wins.
Why is the result not exact after rounding?
Rounded stakes no longer match the odds exactly. The payouts then differ by a few euros between outcomes, and the total stake can differ slightly from the amount you entered.
Sources
- RIS: Gebührengesetz 1957, § 33 TP 17 (Austrian betting fee) (in German)
- Unternehmensserviceportal (USP): Wettgebührenabrechnung (in German)
As of October 2026. Bookmakers' rules, odds and offers change; their current terms and betting rules always apply.
Betting involves risk, even with sure bets: prices move, bets get voided, accounts get limited. Only use money you can do without. Our responsible gambling page lists free help in Austria and Germany.
Information, not betting, legal or tax advice. 18+.