What Is Arbitrage Betting? How Arbs Work, Where They Fail

What is arbitrage betting?

Quick answer
Arbitrage betting places bets on every outcome at different sportsbooks whose prices disagree, so the combined payout beats the combined stake. If two books both offer +110 on opposite sides, splitting $1,000 evenly returns $1,050 whichever side wins. Limits, price changes and voided bets are the real risks.
Written by the Wise Guy Desk, reviewed by Ross Thornton. Page content last changed August 6, 2026.

Arbitrage betting, or arbing, means placing bets on every possible outcome of an event across different sportsbooks whose prices disagree, so that the payout beats your total stake whichever side wins, as long as every bet is accepted at those prices. It relies on temporary pricing gaps between books, and the return is small.

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Reviewed by Ross Thornton, professional sports handicapper

How does arbitrage betting work?

Definition. An arbitrage is a set of bets across books where the implied probabilities add up to less than 100 percent.

Worked example. Book A has Team X at +110 and Book B has Team Y at +110, both 2.10 in decimal. Implied chances are 47.62 percent each, which total 95.24 percent. Staking $500 on each returns $1,050 whichever side wins, a $50 profit on $1,000 (5 percent), assuming both bets are accepted at those prices.

  1. Convert each best price to implied probability: 1 / 2.10 = 47.62 percent.
  2. Add them: 95.24 percent. Under 100 means an arb exists.
  3. Stake in proportion to each probability (here equal): $500 each, payout $1,050.

How arbitrage works

When two books price the same market differently enough, the combined no-vig probabilities dip below 100 percent, creating an arb. You stake each outcome at the book offering the best price, in amounts sized so every result returns more than your total outlay. The profit is small, often 1 to 3 percent, and it only holds if both bets stand at those prices and both books settle the same way.

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A worked example

Book A has Team X at +105 and Book B has Team Y at +105 in a two-way market. Staking both sides in the right proportion returns a profit whichever team wins. An arbitrage calculator takes the two prices and your total stake and outputs exactly how much to put on each side so the return is the same whichever side wins.

The catch

Arbs vanish fast as lines move, require accounts and balances at multiple books, and books limit or restrict bettors who arb aggressively. The margins are thin and the operational effort is high. For most bettors, hunting positive expected value and always taking the best number is a more durable edge than chasing fleeting arbs.

In the Wise Guy tools

Worst case

What you end up with if the less favorable side wins, after fees and rounding stakes to real dollars.

Example: Worst case +$1.20 on $100 = you are up at least $1.20 whichever side wins, if both bets are accepted.

How our tools use it: The smaller of the two results when the stakes are rounded to real dollars, net of exchange fees. It is the return you get whichever side wins, if both bets are accepted at these prices.

12% screening cap

A gap this big between regulated books is usually a posting error a book will cancel, so we never call it actionable.

How our tools use it: A cross above 12% between regulated books is treated as a posting error or a line the book stopped updating (books void obvious errors), so it is never listed as actionable. A screening rule, not proof; below the cap a quote is still not an accepted bet.

Void rules differ

Void rules differ: if one book voids its leg (for example the player sits) and the other settles, this arb can lose. Check both books' void rules.

How our tools use it: A voided leg can turn an arb into a loss. Books settle a voided bet by their own rules: a player prop voids if the player does not play or a pitcher does not start, a live bet can be cancelled on a suspension or a price change, and an exchange or prediction market settles a voided or postponed game by its own rules. One leg can void (stake refunded) while the other loses, so the arb can still lose money. Check both books' void rules before you bet.

Frequently asked questions

Is arbitrage betting legal?

Betting the same event at multiple regulated books is legal, but books may limit or close accounts of bettors who arbitrage regularly. It is against no law, only against the book's interest.

How much can you make arbitrage betting?

Individual arbs usually return 1 to 3 percent. The gains are small and require significant capital across books, and opportunities disappear quickly.

Your next step

  1. 1Learn itArbitrage (this page)
  2. 2Apply itHow to find value bets →
  3. 3Run itArbitrage Calculator →
  4. 4Master itDay 20: Sharp action, handle and line movement →

Related terms

Hedging
Hedging a bet means placing a second wager on the opposite outcome of a bet you already have, so you come out with a profit or a smaller loss whichever way it goes, at the prices you got.
Vig (Juice)
Vig, short for vigorish and also called juice, is the commission a sportsbook builds into its odds.
Expected Value (+EV)
Expected value, or EV, is the average amount a bet would win or lose if you placed it many times over.
Middle
A middle is a pair of bets on opposite sides of two different lines, such as Over 44.5 at one book and Under 47.5 at another.
Betting Exchange
A betting exchange is a marketplace where bettors take each other's offers instead of betting against a sportsbook.
Line Shopping
Line shopping means comparing the price of the same bet across several sportsbooks and exchanges, then placing it wherever it pays the most.
Arbitrage Calculator →Full glossary →

21+. For entertainment and educational purposes, not financial advice. If gambling stops being fun, take a break. 1-800-GAMBLER. Regulated US books only.

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How to use the arbitrage calculator

  1. Find the same market at two books with prices that disagree.
  2. Enter both prices. If the two implied probabilities add to less than 100%, an arbitrage exists.
  3. Use the stakes shown so both outcomes return the same amount.
  4. Check the practical limits before you place anything: bet limits, rule differences, voids and how fast the price can move.

Worked example: Team 1 at +110 and Team 2 at +105

The implied probabilities are 47.62% and 48.78%, which add to 96.40%. Under 100%, so there is a gap.

With $1,000.00 to place, stake $493.98 on Team 1 and $506.02 on Team 2. Either side returns $1,037.35, a $37.35 profit, if both bets are accepted at those prices. Real arbitrage is small and short-lived, and a bet that is limited or voided on one leg leaves you holding the other.

The numbers above are an illustration of the math, not a prediction or a result.

Common questions

What is arbitrage betting?

Betting both sides of a market at different books so the combined return exceeds the combined stake.

Does arbitrage always work?

It only works when both bets are accepted at the stated prices. The risks are limits, voided bets, mistakes and price moves between the two bets.

Why do arbitrage windows close fast?

Books adjust to each other's prices within minutes, so the gap is often gone before the second bet is placed.

Keep going: middle bet calculator, line shopping, how to use arbitrage, hedge calculator.