Quantitative Betting Calculator
Arbitrage Calculator
An arbitrage calculator works out exactly how much to stake on each outcome of an event - priced at different sportsbooks - so you lock in the same return no matter who wins. Enter the odds for every side and your total stake, and it splits the stakes by implied probability and shows your guaranteed profit and arb percentage.
How the arbitrage calculator works
Enter each outcome's best price
For a two-way market that's the best price on one side at one book and the best price on the other side at a different book. The bigger the gap between books, the bigger the arb.
It checks whether an arb exists
The calculator converts every price to an implied probability and adds them up. If the total is below 100%, the market is arbitrageable and a guaranteed profit is available; above 100% there is no arb.
Stakes are sized to pay the same
It divides your total stake across the outcomes in proportion to their implied probability, so every result returns an identical amount - that's what makes the profit risk-free.
Arbitrage formula
Arb % = 1 − (1/decimalA + 1/decimalB + …). If the sum of 1/decimal for every outcome is below 1, an arb exists. Each stake = Total × (1/decimalᵢ) ÷ Σ(1/decimalⱼ).
Example — Back Team A at +110 (decimal 2.10) at one book and Team B at +105 (decimal 2.05) at another. Implied probabilities are 47.6% + 48.8% = 96.4% - under 100%, so a ~3.7% arb exists. On a $1,000 total you'd stake $494.12 on Team A and $505.88 on Team B and clear $37.34 whichever side wins.
Frequently Asked Questions
What is a sports arbitrage bet?
An arbitrage bet (or 'arb') backs every outcome of an event at different sportsbooks whose combined odds guarantee a profit no matter the result. It works because different books sometimes post prices that disagree enough to leave a gap.
Is arbitrage betting legal?
Yes. Arbitrage betting is legal for bettors and breaks no law. Individual sportsbooks may limit accounts they identify as sharp, but that is a private house policy, not a legal restriction.
How much money can you make arbitrage betting?
Individual arbs are usually small - often 1-5% of the stake - and windows close fast. Profit comes from volume and speed, not size. Larger edges exist but disappear quickest.
Why did my arbitrage opportunity disappear?
Arbs vanish when a book corrects its price or another bettor moves the line. That's why speed matters - always confirm the exact odds at the book before staking, since the market can move between the calculator and your bet slip.
Related Calculators
Apply This Math to Live Vegas Markets
Check the Live Multi-Sport Odds Board for current spreads, moneylines, and totals across NFL, NCAAF, NBA,NCAAB, MLB, NHL, UFC, Soccer, and Tennis, or explore our Betting School curriculum for deeper handicapping lessons.