Arbitrage betting (or "arbing") means betting every outcome of a market at different sportsbooks, at prices that guarantee a profit no matter who wins. It is possible because books disagree on prices. It is also smaller, rarer and more fragile than most people expect.
How an arb works
Two books disagree on a tennis match:
- Book A: Player 1 +115 (decimal 2.15)
- Book B: Player 2 −105 (decimal 1.952)
Implied probabilities: 46.51% + 51.22% = 97.73%. Below 100%, so there is an arb.
Stake $500 in total, split by implied probability:
- Player 1 at Book A: $500 × 46.51 / 97.73 = $237.95 → returns $511.61
- Player 2 at Book B: $500 × 51.22 / 97.73 = $262.05 → returns $511.61
Whoever wins, you get back $511.61 on $500: a 2.3% locked-in return at those prices. The arbitrage calculator does the split for you. (Arbitrage stake calculator guide.)
The arb formula
- Convert each side's best price to decimal odds.
- Add up 1 ÷ decimal for every outcome.
- If the sum is below 1, it is an arb. Profit % = 1 ÷ sum − 1.
- Stake on each outcome = total stake × (1 ÷ its decimal) ÷ sum.
How big are arbs?
Most real arbs at US books are 0.5% to 3%. Anything over 5% usually means a stale price, a rules mismatch or an error that might be voided. Arbs appear most often on:
- Player props
- Lower-profile games and leagues
- Moments after news, when books update at different speeds
- Live betting (high risk of price changes)
Arbitrage vs +EV betting
| Arbitrage | +EV betting | |
|---|---|---|
| Risk per bet | Near zero if both legs stand | Normal betting variance |
| Typical return | 0.5–3% per arb | 1–4% average edge |
| Frequency | Uncommon | Common |
| Capital needed | Money at many books | Less |
| Limit risk | High: books spot arbers fast | Moderate |
Many experienced bettors prefer +EV because it offers far more opportunities, while arbs are a nice addition when they appear. (What is +EV betting?.)
The real risks
Arbitrage is "risk-free" only if everything goes right:
- Price changes before you place the second leg
- Voided legs on obvious errors, leaving you with one unhedged bet
- Rule differences (overtime, retirements, player-not-playing)
- Limits cutting your second leg's stake
- Account restrictions from books that dislike arbers
(Arbitrage betting risks · Do sportsbooks limit arbers?.)
Is arbitrage betting legal?
Yes, betting at licensed books is legal where sports betting is legal, and arbitrage is just betting at two of them. Books can still limit or close accounts under their terms. (Is arbitrage betting legal?.)
Finding arbs
Arbs are rare and short-lived, so manual searching rarely works. Software scans every book continuously. The OddsHype arbitrage page lists live arbs across books legal in your state, with stale-quote checks so legs are recent, and Sharp plans add instant arb alerts. (How to find arbitrage bets.)
Frequently asked questions
Is arbitrage betting really risk-free?
In theory, yes. In practice, price changes, voided bets, rule differences and limits create real risk that must be managed.
How much can you make from arbitrage betting?
Typical arbs return 0.5–3% of the total stake. Profit depends on how many you find and how much the books let you bet.
Do sportsbooks allow arbitrage betting?
It is legal, but books may limit accounts they identify as arbitrage bettors.