Arbitrage Betting Explained: How to Lock In Guaranteed Profit

Most betting strategies ask you to accept some risk in exchange for a positive expected return. Arbitrage betting is the rare exception – done correctly, it removes the risk almost entirely. You’re not betting on an outcome. You’re betting on all of them at once, at prices that don’t agree with each other, and collecting a small guaranteed profit no matter what happens on the field.

It sounds like a loophole because it basically is one. It exists because different sportsbooks price the same game independently, and every so often two books disagree enough that you can bet both sides and come out ahead regardless of the result.

The short answer

Arbitrage betting (often shortened to “arbing”) means placing bets on every possible outcome of an event across two or more sportsbooks, at odds that combine to less than 100% implied probability. When the implied probabilities of your combined bets add up to under 100%, you can size each leg so that every outcome pays you back more than you staked in total. The game’s actual result stops mattering – you win a fixed, known amount either way.

This only works because sportsbooks price independently and don’t always agree. One book might be slow to react to injury news. Another might be shading a line to balance its own action. When those gaps get big enough, an arbitrage opportunity opens up – briefly.

How the math actually works

Every price implies a probability. Add up the implied probabilities of all outcomes at a single sportsbook and you’ll almost always get a number over 100% – that extra is the vig, the book’s built-in cut. Arbitrage opportunities appear when you shop the same market across multiple books and the best available price on each side, combined, prices out to under 100%.

Step 1 – Convert each side’s odds to implied probability.
For positive American odds: 100 / (odds + 100)
For negative American odds: -odds / (-odds + 100)

Step 2 – Add the implied probabilities of every outcome together, using the best price available for each.

Step 3 – If the total is under 100%, you have an arbitrage opportunity. The size of the gap below 100% is your guaranteed return.

Worked example

Say a tennis match has two outcomes. Sportsbook A offers Player 1 at +105. Sportsbook B offers Player 2 at +105.

Player 1 implied probability: 100 / 205 = 48.8%
Player 2 implied probability: 100 / 205 = 48.8%
Combined: 97.6%

That’s under 100%, which means there’s a 2.4% guaranteed edge available if you bet both sides in the right proportion. To lock in an equal profit regardless of which player wins, you’d stake roughly $488 on Player 1 at Book A and $488 on Player 2 at Book B for every $1,000 you’re willing to deploy. Whichever side wins, that leg pays out $1,000 total ($488 stake plus $512 profit at +105), while the other leg loses its $488 stake – netting you about $24 in guaranteed profit on $976 committed, regardless of the result. Do that reliably and consistently, and it compounds – the tradeoff is that each individual opportunity is small, brief, and requires moving real money across multiple accounts fast.

The three main types of arbitrage bets

Not all arbs look the same. The two-way tennis example above is the simplest case, but arbitrage opportunities show up in a few different shapes:

Two-way arbs cover markets with exactly two outcomes – moneylines in tennis, spreads, and totals (over/under). These are the most common and the easiest to calculate, since you’re only balancing two legs against each other.

Three-way arbs apply to markets with a draw, like soccer moneylines. You need all three implied probabilities (home, away, draw) to add up to under 100% across your chosen books, which is a rarer and usually smaller gap than a two-way arb, but it does happen when books disagree on how likely a draw is.

Live or in-play arbs open up mid-event, when one book is slow to move a line after a scoring play, injury, or momentum shift that another book has already priced in. These pay the widest margins because the mispricing is often severe – but they also close the fastest, sometimes within seconds, which makes them the hardest type to execute reliably without automated odds-scanning.

How bettors actually find arbitrage opportunities

Nobody profitably arbs by refreshing sportsbook apps and doing implied-probability math by hand. The margins are too thin and the windows too short. In practice, arb hunting means running (or subscribing to) software that pulls live odds from dozens of sportsbooks simultaneously, cross-references every market for combined implied probabilities under 100%, and flags the gap the moment it appears.

That’s also the point where a lot of arb tools fall short: scanning speed matters less than what you’re comparing against. A tool that only cross-references sportsbooks against each other is really just measuring how much two books disagree – useful, but it tells you nothing about which side is closer to fair. Anchoring the comparison to an independent, two-sided pricing source (rather than just another sportsbook line) gives you a cleaner read on which price is actually mispriced, not just which two prices happen to be furthest apart.

Why arbitrage betting is riskier than it sounds

The math is clean. The execution isn’t.

Arb opportunities close fast. Lines move the moment enough money hits one side, so the gap you calculated when you found it can shrink or disappear entirely by the time your second bet lands – leaving you with a mismatched position instead of a locked-in one. That’s the single biggest way arbing goes wrong in practice: one leg fills, the other doesn’t, and you’re just holding a normal directional bet again.

Sportsbooks also actively police this. Accounts that consistently bet both sides of a market across different books get flagged, limited, or closed – arbitrage betting is one of the fastest ways to get a sportsbook to cap your stakes to $5 a bet. Unlike +EV betting, which can be disguised inside a broader betting pattern, arbing leaves an obvious fingerprint: opposite bets on the same game, placed within minutes of each other, sized to hedge exactly.

There’s also a capital efficiency problem. Real arb margins in liquid markets are usually under 2%, and you need your full stake sitting in multiple sportsbook accounts simultaneously to act on them. That’s a lot of capital tied up for a return that’s often smaller than what a well-selected +EV bet offers on its own, without the account-limiting risk that comes from an obvious two-sided betting pattern.

Where arbitrage and +EV betting diverge

+EV betting accepts variance in exchange for a real, sustained mathematical edge over many bets – you can lose plenty of individual bets and still be ahead over a large enough sample, and the betting pattern itself doesn’t scream “arbitrage” to a book’s risk team. Arbitrage betting removes the variance but caps the edge at whatever tiny gap the market handed you, and it’s a much easier pattern to get flagged for.

That’s part of why Edge treats arbitrage as one signal among several rather than a standalone strategy. The same scanning infrastructure that flags +EV opportunities against Kalshi’s fair-value pricing also catches genuine cross-book arbitrage gaps when they open up – logged and surfaced the moment they’re found, since a window that’s live for two minutes is worthless if you see it twenty minutes later. Anchoring to Kalshi’s two-sided exchange pricing instead of sportsbook consensus also means Edge is comparing against a cleaner fair-value baseline, which matters just as much for spotting a real arb gap as it does for spotting mispriced +EV lines.

The takeaway

Arbitrage betting is real, mathematically sound, and genuinely low-risk when executed cleanly – but “low-risk” isn’t “no-risk,” and the risks that remain (execution timing, account limits, capital tied up across books) are operational, not statistical. It works best as a tool in a broader toolkit, not a strategy you build an entire bankroll around.

See how Edge surfaces both +EV and arbitrage opportunities against a Kalshi-anchored fair-value line, with every alert timestamped and tracked in the open, at automatehive.net/edge.

Not betting advice. Bettors must be 21+. Bet responsibly — only wager what you can afford to lose. Gambling problem? Call 1-800-GAMBLER.