What is a betting arbitrage?

An arbitrage exists when the best price on each side of a market, taken at different sportsbooks, adds up to less than 100% implied probability. Backing both sides then returns a profit whichever way the event lands.

How do you calculate an arb?

Turn each price into an implied chance (1 ÷ decimal odds) and add them. Under 100% means an arb; the margin is 1 ÷ that total, minus 1. Example: +115 and -105 imply 46.5% + 51.2% = 97.7%, a 2.3% margin.

How do you split the stake on an arb?

Give each side your total stake × its implied chance ÷ the combined implied chance. Both outcomes then return the same amount.

Is arbitrage betting legal?

Yes, placing bets at different licensed sportsbooks is legal in US states where sports betting is legal. Books can still limit accounts that only bet arbs, and they may void bets placed at obvious pricing errors.

How much can you make from arbitrage betting?

Most arbs lock in 1% to 3% of the total stake, so $500 across both sides usually returns $5 to $15 profit. They close fast, and a price move before the second bet can erase the margin.

Arbitrage calculator

Enter the best price you can get on each side of a market, from any two sportsbooks, to see whether an arb exists and how to split the stake.

Side A price (book 1)

Side B price (book 2)

Total stake

Arbitrage available

Combined market: 97.73%
Return on stake: +2.27%
Locked profit: $11.61
Stake on side A: $237.96
Stake on side B: $262.04
Return either way: $511.61

Both sides return the same amount, so the profit stands whichever way the event lands — as long as both bets are accepted at these prices.

Finding the price difference is only the beginning.

STRATOS Edge adds sportsbook comparison, +EV analysis and line movement. Prices can move, and books may not accept the displayed price.

Explore Edge

How arbitrage works

Every sportsbook prices a market at over 100% — that gap is its margin. When two books disagree enough, the best price on each side can add up to under 100%. Backing both sides in the right proportion then returns the same amount whichever way the event lands.

The split is proportional to each side's implied chance, so both outcomes pay out equally. Arbs are usually thin — often 1% to 3% — and short-lived, so the price you see is not always the price you get.

Be aware of the practical limits: prices move while you place the second leg, books void obvious errors, and accounts that only ever bet arbs tend to get limited. Treat the number here as the best case at the prices you entered.

Stratos compares live prices across real books. Remove the vig on a single book's market, or convert a price.

Worked example

Book A has Team 1 at +115 (decimal 2.15) and Book B has Team 2 at -105 (decimal 1.952). Implied chances: 1 ÷ 2.15 = 46.5% and 1 ÷ 1.952 = 51.2%, which add to 97.7%. Under 100%, so it is an arb with a margin of about 2.3%.

With $500 total: put $500 × 46.5 ÷ 97.7 = $237.95 on Team 1 and $262.05 on Team 2. Team 1 winning pays $237.95 × 2.15 = $511.60; Team 2 winning pays $262.05 × 1.952 = $511.60. Either way you get back about $511.60 — an $11.60 profit, before any price moves.

Arbitrage questions people ask

What is a betting arbitrage?: An arbitrage exists when the best price on each side of a market, taken at different sportsbooks, adds up to less than 100% implied probability. Backing both sides then returns a profit whichever way the event lands.
How do you calculate an arb?: Turn each price into an implied chance (1 ÷ decimal odds) and add them. Under 100% means an arb; the margin is 1 ÷ that total, minus 1. Example: +115 and -105 imply 46.5% + 51.2% = 97.7%, a 2.3% margin.
How do you split the stake on an arb?: Give each side your total stake × its implied chance ÷ the combined implied chance. Both outcomes then return the same amount.
Is arbitrage betting legal?: Yes, placing bets at different licensed sportsbooks is legal in US states where sports betting is legal. Books can still limit accounts that only bet arbs, and they may void bets placed at obvious pricing errors.
How much can you make from arbitrage betting?: Most arbs lock in 1% to 3% of the total stake, so $500 across both sides usually returns $5 to $15 profit. They close fast, and a price move before the second bet can erase the margin.