Arbitrage betting is one of the few ways to lock in a profit on sports no matter who wins. This guide explains how arbitrage betting works, how to spot an arb, and how to size each side, with a worked example you can run yourself in our free arbitrage betting calculator.
How Arbitrage Betting Works
Every set of odds implies a probability. When you add up the implied probabilities for both sides of a two-way market and the total comes to less than 100 percent, the sportsbooks have priced the event loosely enough that you can bet both sides and come out ahead. Because one side always wins, splitting your stake correctly turns that pricing gap into a guaranteed return.
How to Spot an Arb
Take the best available price for each outcome, ideally from two different sportsbooks, and convert both to decimal odds. Add 1 divided by each price. If the sum is under 1.00 (100 percent), you have an arbitrage opportunity. The further below 100 percent, the bigger the guaranteed profit. The fastest way to check is to drop the two prices into the arbitrage calculator, which also tells you exactly how much to stake on each side.
Worked Example
Suppose Team A is +120 (decimal 2.20) at one book and Team B is +110 (decimal 2.10) at another. The implied probabilities are 45.45 percent and 47.62 percent, a total of 93.07 percent. That is under 100 percent, so an arb exists. On a $100 total stake you bet about $48.84 on Team A and $51.16 on Team B. Whichever team wins, the payout is roughly $107.45, a guaranteed profit of about $7.45, or 7.45 percent ROI.
The Catches to Know
Arbs are real but small, usually a few percent, so the money comes from doing many of them accurately. Lines also move fast, so an arb can vanish in minutes, and sportsbooks may limit or close accounts that arbitrage aggressively. Plan both legs before you place them and act quickly. Arbitrage betting is legal in most places, but always check your local rules and bet responsibly.
Free Printable Arbitrage Worksheet
To plan an arb on paper before the line moves, download the free printable worksheet. It has fields for each sportsbook, market, odds and stake, plus a spot to work out your guaranteed profit and ROI.
Download the Arbitrage Worksheet (PDF)
Run Your Own Numbers
Ready to try it? Open the free arbitrage betting calculator, enter two opposing prices, and it will show whether an arb exists and how to split your stake. See also our Odds Converter and Implied Probability Calculator.
Arbitrage Betting FAQ
What is arbitrage betting? Arbitrage betting, or sports arbitrage, is backing every outcome of an event at odds that together guarantee a profit no matter the result. It relies on two sportsbooks pricing the same event differently enough that the combined implied probability falls below 100 percent.
How do you calculate an arbitrage bet? Convert each side’s odds to decimal, add the implied probabilities (1 divided by each), and if the total is below 1.00 an arb exists. Then stake each side in proportion to its implied probability so both outcomes return the same payout. Our arbitrage calculator does this instantly.
Is arbitrage betting worth it? Arbs usually return a few percent per bet, so profits come from volume and discipline rather than big single wins. The main limits are small edges, fast-moving lines, and sportsbooks restricting accounts that arb heavily.
Do you need two accounts for arbitrage betting? Usually yes. The two best prices for opposite outcomes are typically at different sportsbooks, so you place one leg at each. Having funded accounts at several books ready to go is what makes arbing practical before a line moves.
