Arbitrage Betting: How to Find and Exploit Risk-Free Opportunities
Last updated:
Arbitrage betting — “arbing” — exploits the fact that different books price the same event differently. When the gap is wide enough, you can back every outcome across multiple books and lock in a profit no matter what happens.
This guide explains how an arb works, how to calculate the arb percentage and stake split, where to find opportunities, and the real-world risks that stop arbing from being free money.
How an arb works
An arbitrage exists when the combined implied probability of every outcome, taken at the best available price across books, is less than 100%. Because each book shades its line differently, occasionally the best “Team A” price at one book and the best “Team B” price at another sum to under 100% — a guaranteed margin.
Example: Book 1 has Team A at +110 (47.6% implied) and Book 2 has Team B at +110 (47.6% implied). Together that is 95.2%, leaving a 4.8% edge. Staking both sides in the right proportion returns more than you risked regardless of the result.
Calculating the arb
Start by converting every price to implied probability — our odds converter does this in one step. Add the best price for each outcome together. If the total is below 100%, the difference is your arbitrage margin; if it is above, there is no arb.
To size the bets, split your total stake in proportion to each outcome’s implied probability so both sides return the same amount. The vig calculator helps here too: by exposing the implied probabilities and hold on each market, it makes spotting a sub-100% combined book straightforward.
- Convert each outcome’s best price to implied probability.
- Sum them — below 100% means an arb exists, and the gap is your margin.
- Split stakes in proportion to implied probability so every outcome pays equally.
- Account for fees and exchange commission before declaring a profit.
Where to find arbs
Arbs appear most often when books disagree — around breaking news, between a slow-moving book and a sharp one, or between a sportsbook and a prediction market pricing the same event. Comparing the best price per outcome across many venues is exactly what OddsGrab surfaces, which is the first step in spotting them.
They are usually small (1–5%) and short-lived, vanishing as books adjust. Promotional pricing, boosted odds, and bonus-bet conversions create larger temporary gaps, which is why many bettors combine arbing with welcome-offer hunting.
The risks
Arbing is “risk-free” only in theory. In practice the biggest risk is account limits: books quickly restrict or ban bettors who only ever take arbs, because the pattern is obvious. Spreading action and avoiding suspicious bet sizing helps, but the threat is real.
Other risks are mechanical: a line can move before you place the second leg, leaving you one-sided; a book can void a bet on a “palpable error”; and stake limits can stop you completing the arb at size. Treat arbing as a disciplined grind with execution risk, not a money printer.
Frequently asked questions
- What is arbitrage betting?
- Arbitrage means backing every outcome of an event across different books at prices that, combined, imply less than 100% probability. Because each book prices independently, the gaps occasionally let you stake all sides in proportion and lock in a profit regardless of the result.
- How do I calculate an arbitrage percentage?
- Convert each outcome’s best available price to implied probability and add them together. If the total is below 100%, an arb exists and the difference is your margin — a sum of 95% means a 5% edge. If it is above 100%, there is no arbitrage.
- How do I split my stakes on an arb?
- Divide your total stake in proportion to each outcome’s implied probability so every result returns the same amount. Tools that expose implied probability per side make this quick; just remember to factor in any exchange commission or fees before counting the profit.
- Where do arbitrage opportunities come from?
- They appear when books disagree — around breaking news, between slow and sharp books, or between a sportsbook and a prediction market on the same event. Promotions and boosted odds create larger temporary gaps, which is why comparing the best price per outcome is the starting point.
- Is arbitrage betting really risk-free?
- Only in theory. The main risk is account limits — books restrict bettors who consistently arb, because the pattern is easy to spot. Lines can also move before you place the second leg, and bets can be voided on palpable errors, so arbing carries genuine execution risk.
- Can I arb between a sportsbook and a prediction market?
- Sometimes. When a sportsbook’s de-vigged price and a prediction-market contract price diverge enough on the same outcome, the combined implied probability can fall below 100%. Converting both to the same scale is how you spot it, which is exactly what comparing venues on OddsGrab enables.
Helpful tools
Related guides
Educational content for informational purposes only. Not betting or financial advice. Please gamble responsibly. 21+ where applicable.