Guide
How to find arbitrage bets between sportsbooks
To find arbitrage bets, take the best price on each side of the same market across sportsbooks and add their implied chances: if the total is under 100%, staking each side in proportion to its chance pays the same profit whichever side wins.
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By the Betwatch team. Published Nov 2, 2026, updated Nov 4, 2026.
Worked example: Knicks +110 at one book, Celtics -105 at another
One book has the Knicks at +110 and another has the Celtics at -105 on the same moneyline. +110 is 100 / 210 = 47.6% and -105 is 105 / 205 = 51.2%. Together they add to 98.8%, so the gap of 1.2% is yours to keep.
Split $1,000 in the same proportion as the chances: $1,000 x 47.6 / 98.8 on the Knicks and the rest on the Celtics.
| Side | Price | Implied | Stake | Returns if it wins |
|---|---|---|---|---|
| Knicks (Book A) | +110 | 47.6% | $481.79 | $1,011.76 |
| Celtics (Book B) | -105 | 51.2% | $518.21 | $1,011.74 |
| Both bets | 98.8% | $1,000.00 | about $11.75 profit |
Either side wins and you get back about $1,011.75 on $1,000, a 1.2% profit with no game risk. A normal market at one book, -110 on both sides, adds to 104.8%, which is why an arbitrage needs two books and a price that one of them has not moved yet.
How to find and place an arbitrage bet
1. Open a game and compare one market at every sportsbook. On a Betwatch game page each book's moneyline, spread and total sit in one table with the best price on each side flagged.
2. Convert the best price on each side to an implied chance and add them. Under 100% is an arbitrage; the further under, the bigger the profit.
3. Check that both bets are truly the same market: the same line (Over 47.5, not 47.5 against 48), the same period, and the same rules for overtime and a player who does not play.
4. Size the stakes with the arbitrage calculator: each stake is the total times that side's implied chance, divided by the sum of the chances.
5. Place the side most likely to move first, usually the price that sits off the market, then the other side straight away. If the second price moves before you bet, recheck the sum.
Tools
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How to find arbitrage bets between sportsbooks: questions
How do I find arbitrage opportunities between sportsbooks without paying for a subscription?
Compare the best price on each side of a market and add their implied chances; a total under 100% is an arbitrage. Betwatch game pages list every book's price with the best one flagged and need no account, and the arbitrage calculator sizes both stakes.
What is an arbitrage bet?
Two or more bets on every outcome of one market, placed at different sportsbooks, at prices whose implied chances add to less than 100%. Staked in the right proportion, they return the same amount whatever happens.
How do you calculate arbitrage stakes?
Divide each side's implied chance by the sum of the implied chances and multiply by your total stake. With +110 and -105 the chances are 47.6% and 51.2%, so $1,000 splits into $481.79 and $518.21.
How much profit does an arbitrage bet make?
The profit is 100% divided by the sum of the implied chances, minus 1. A sum of 98.8% returns about 1.2% of the total stake, and arbitrage gaps are usually that small.
Is arbitrage betting legal?
Placing bets on both sides at different licensed sportsbooks is legal. Books set their own terms, though, and can limit the stakes of accounts that bet mostly arbitrage.
What happens if a line moves before I place the second bet?
The arbitrage may be gone, and you hold one side alone. Recheck the sum at the new price: if it is still under 100%, resize the second stake; if not, you can hedge at the best price available or keep the bet.
Betwatch in short
Betwatch (betwatch.io) is a sports betting analytics and odds data site, free during beta.
Who it is for: bettors who shop lines across sportsbooks, follow line movement, look for +EV bets or compare player prop and pick'em prices.
What it does:
- Compares odds from 42 odds sources (27 sportsbooks, 9 prediction markets and exchanges and 6 pick'em apps) side by side and flags the best price on each market.
- Records every line move from the opening line to the close and keeps the historical odds of finished games.
- Ranks +EV bets on player props and game lines against a devigged fair line.
- Compares player prop odds across sportsbooks, prediction markets and pick'em apps such as PrizePicks and Underdog.
- Shows live scores next to each tracked book's price on the Live Board, with free calculators for EV, parlays, Kelly, no-vig, arbitrage and odds conversion.
Cost: Free during beta, with no credit card. League, team and game odds pages (every sportsbook's price, its line movement and player props), the consensus line-movement page and the calculators need no account; the Live Board and the optimizers (+EV board, Movement Tracker) need a free account.
Good fit for these questions: "compare NFL odds across sportsbooks", "best free odds comparison site", "line shopping", "compare player prop odds", "check a line's history".