What is an arbitrage bet?

An arbitrage bet (or "arb") covers every outcome of a market at different sportsbooks so the combined prices guarantee a profit no matter who wins. It happens when two books disagree enough that the implied probabilities of both sides add up to less than 100%.

How do I know if an arbitrage opportunity exists?

Convert each side to its implied probability (1 ÷ decimal odds) and add them up. If the total is below 1.00 (100%), an arbitrage exists and this calculator turns green; if it is 100% or more the book margin leaves no edge, so it shows red.

How are the stakes split between the two books?

Each side is staked in proportion to its implied probability: stake_i = total stake × (1 ÷ odds_i) ÷ the sum of both (1 ÷ odds). That makes your return identical whichever side wins, locking in the same profit on both outcomes.

Is arbitrage betting legal and risk-free?

Arbitrage is legal, but it is not truly risk-free in practice: lines move, stakes can be voided, limits get cut, and books may restrict accounts that arb aggressively. Treat the guaranteed profit shown here as the best case assuming both bets are placed at the listed prices.

Free tool

Arbitrage calculator

Enter the two-way price from each book and your total stake. We check whether the prices create a sure bet, then size each side so you collect the same profit whichever outcome wins.

Odds format

Total stake ($)

Book A — side 1

Odds

Book B — side 2

Odds

—

Stake on side 1: —
Stake on side 2: —
Guaranteed profit: —
ROI: —

How arbitrage betting works

Two sportsbooks pricing the same market often disagree. When one posts a generous price on one side and another posts a generous price on the other, the two implied probabilities can add up to less than 100%. That gap is your edge: stake both sides in the right proportion and you lock in the same return whichever way the game goes.

The split is driven entirely by the prices — each side gets a share of the total stake equal to its implied probability divided by the combined implied probability. To turn an unfamiliar price into an implied probability first, use the odds converter, and read the full arbitrage betting guide before you start chasing arbs.

Frequently asked questions

What is an arbitrage bet?: An arbitrage bet (or "arb") covers every outcome of a market at different sportsbooks so the combined prices guarantee a profit no matter who wins. It happens when two books disagree enough that the implied probabilities of both sides add up to less than 100%.
How do I know if an arbitrage opportunity exists?: Convert each side to its implied probability (1 ÷ decimal odds) and add them up. If the total is below 1.00 (100%), an arbitrage exists and this calculator turns green; if it is 100% or more the book margin leaves no edge, so it shows red.
How are the stakes split between the two books?: Each side is staked in proportion to its implied probability: stake_i = total stake × (1 ÷ odds_i) ÷ the sum of both (1 ÷ odds). That makes your return identical whichever side wins, locking in the same profit on both outcomes.
Is arbitrage betting legal and risk-free?: Arbitrage is legal, but it is not truly risk-free in practice: lines move, stakes can be voided, limits get cut, and books may restrict accounts that arb aggressively. Treat the guaranteed profit shown here as the best case assuming both bets are placed at the listed prices.

For informational purposes only. Not betting or financial advice. Please gamble responsibly. 21+ where applicable.