What Is Arbitrage Betting? Formula, Example, Surebet Data

Arbitrage betting means placing bets on every outcome of one event at different sportsbooks so that the winning bet pays more than the total staked, whatever the result. Such a set of bets is called a surebet, or an arb. It appears when books price an event differently: add up the inverse odds of the best price on each outcome, and the sum comes out below one. The profit is locked into the prices in advance, but the gap does not last long.

Over 30 days, from October 6 to November 5, 2026, the Dozor scanner recorded 4,829,879 surebet episodes in esports and prediction markets — about 6,700 an hour — among them 1,397,673 distinct surebets. Half of the episodes lasted 2 seconds or less, 3.9% lasted over a minute — roughly 260 surebets an hour. The median ROI was 3.2%. How we count is in the methodology.

Synonyms: surebet, arb, arbitrage bet

How to spot a surebet

For two outcomes with odds k₁ and k₂ at different books, a surebet exists if

1/k₁ + 1/k₂ < 1

For three outcomes (win, draw, loss), you add up three inverse odds. The smaller the sum, the higher the return: ROI equals 1 / sum − 1.

At a single sportsbook, the sum of inverse odds is always above one — that is its margin: at 1.90 on both outcomes, the sum is 1.0526 and the margin is 5.26%. A surebet appears only when the prices for different outcomes come from different venues and the gap covers the margin of both. You can check a pair of odds and split a bankroll in the arbitrage calculator; stake formulas and two-way and three-way examples are in the article on how to calculate arbitrage bets.

Example: Polymarket vs a sportsbook

On a prediction market, the price is the cost of a share in cents: a winning share pays $1, so the odds equal 1 / price. A hypothetical example: a CS2 match, on Polymarket a "MOUZ (−1.5)" share costs 46¢, a sportsbook offers 2.05 on "G2 (+1.5)". The outcomes are opposite: either MOUZ wins by two maps, or G2 takes at least one map.

The profit is $20.71 on any outcome. Without fees the ROI would be 5.51%: the Polymarket taker fee on sports markets — 0.05 × price × (1 − price) per share — took about a quarter of the gap. Settlement rules differ too: if the match is canceled, Polymarket settles the market 50-50 under its market rules, while Pinnacle, for example, voids bets on a match not started within 30 hours. Then this example ends at plus $14.36 instead of $20.71.

Types of surebets

By number of outcomes. Two-way: winner with no draw, handicap, over/under — the bulk of esports. Three-way: win, draw, loss — three bets at three books, and placing them before any of the three prices moves is harder.

By result:

A middle with numbers: over 26.5 rounds at 1.95 and under 27.5 at 1.95, 500 on each bet. Any score except exactly 27 rounds ends at minus 25; 27 rounds ends at plus 950. A negative surebet is only used to clear a bonus, when a small loss costs less than clearing it with regular bets.

By timing. Live — during the match, prematch — before it starts. Live gives most of the volume, while prematch surebets last longer: the numbers are below.

Where surebets come from

• Different estimates. Books price probabilities independently, so their estimates of the outcome can differ.
• Different line speed. In live, one book has already updated its odds after an in-game event, the other has not. Such surebets last seconds; how many seconds ago a book updated its price is the price age.
• Different kinds of venues. On a prediction market, the price is set by traders, not by a sportsbook's analyst. Over 30 days, Polymarket took part in 438,206 surebet episodes — 9.1% of all — most often paired with Duel and 1xBet.
• Different line providers. Brands of one provider share a single line and give no surebets with each other — that is a feed group. The scanner does not show such pairs.

Dozor data

What it means: switching tabs by hand, you can only catch surebets that last tens of seconds — a few hundred an hour out of 6,700. There are 14 times fewer prematch surebets than live ones, but 40.8% of them hold for over a minute. The most episodes involve 1xBet (1.69 million), Duel (799,000) and Thunderpick (789,000); the Polymarket exchange accounts for 438,000. In total, Dozor reads the lines of 27 bookmakers and 3 exchanges.

Who arbers are

An arber is a bettor who works surebets: keeps money at several books, finds gaps with a scanner and places every leg within seconds, before the prices move. An arber wins on the price gap, not on a prediction, so for a sportsbook this is a customer who profits from its delays and line errors. Hence the restrictions below.

Is it legal, and do sportsbooks ban arbers?

We don't give legal advice: whether betting is legal depends on your country and the sportsbook's licence. What the law and regulators say in the US, the UK, Canada and Australia, with official sources: Is arbitrage betting legal?

What does exist for sure is each book's rules. A sportsbook decides which bets to accept and may void a bet placed at a wrong price. For example, Pinnacle's general rules say: "All bets will be accepted or rejected purely at Pinnacle's discretion" and "If there is an obvious error in the odds or limit of a market, bets on that market may be voided" (rules checked on November 5, 2026). How books restrict arbers — betting limits, voided bets, checks — and what to do about it is covered in the article on why sportsbooks limit accounts.

Where to start

1. Run the numbers in the calculator. Enter the odds from two books: it shows whether there is a surebet and splits your bankroll into stakes.
2. Open the scanner on Free. No card and no time limit: surebets with ROI under 1% are shown in full, for the rest you see their number and the best ROI.
3. Find out your books' limits. A surebet's size is capped by its smallest leg: in the scanner you set it with "Stake at this bookmaker", and why limits drop over time is covered in the article on account limiting.

FAQ

Is a surebet guaranteed profit?

Mathematically yes, if every bet is accepted at the calculated odds. In practice, seconds pass between bets: the odds may move, a bet may be rejected because of a limit or voided. It is low-margin work with operational risk, not a guarantee.

What ROI do surebets usually have?

In Dozor data over 30 days, the median is 3.2%; 11.6% of episodes are below 1%, 8.4% are at 10% or above. A surebet above 10% is worth checking for a line error: a book may void a bet placed at an obvious error.

Are there prematch surebets?

Yes: 318,672 episodes over 30 days, with a median lifetime of 38 seconds versus 2 in live. More on the modes on the live surebets and prematch surebets pages.

How is a surebet different from a value bet?

A value bet is a single bet at odds above the fair price: the risk of losing remains, and the edge only shows over many bets. A surebet covers every outcome at once.

Sources

Checked on November 5, 2026.

• Polymarket fees: the taker fee is shares × feeRate × price × (1 − price), feeRate on sports markets is 0.05, makers pay nothing.
• Polymarket "Map Handicap" market rules (CS2, November 5, 2026): a canceled match settles 50-50.
• Pinnacle betting rules: general rules (accepting bets, obvious errors), Esports section (a match not started within 30 hours is void).
• Dozor: data — methodology.