How arbitrage scanners work, explained without jargon

The five steps of a scanner

1. Collect odds from as many bookmakers as possible, as fresh as possible.
2. Match them: which events and markets at different bookmakers are the same?
3. Normalise them: turn rules, fees and commissions into comparable prices.
4. Calculate: for each market, take the best price for each outcome and check whether 1/odds₁ + 1/odds₂ (+ 1/odds₃) is below 1.
5. Filter and show: drop stale prices and likely errors, work out the stakes, rank the rest.

Step 4 is the same calculation you do by hand in the arbitrage calculator. Everything else exists to make sure the inputs to that sum are trustworthy.

Where the odds come from

There are two basic routes. A provider can buy odds from a commercial data supplier that collects prices from many bookmakers and delivers them through an API (a programming interface). Or it can read the bookmakers' websites itself. The second route often reaches more bookmakers, but it is technically fragile, breaks whenever a site changes and may breach the bookmakers' terms of use.

With an API, the software usually requests odds at intervals rather than receiving a live stream. Every request costs money or quota, so a scanner has to decide what to check and how often. Matches starting soon change faster and are checked more often than matches a week away.

How ArbVantage does it: we take odds from a commercial odds data provider. Events in the next few hours are polled much more often than events days away, and leagues where sure bets appear more often get more requests. Every price is stored with the time it was last seen. The details are in our methodology.

Matching events and markets

One bookmaker writes "SK Rapid", the next "Rapid Wien", a third "Rapid Vienna". Kick-off times differ by a few minutes; women's and men's teams, under-21 and first teams have almost identical names. A scanner has to recognise these entries reliably as the same match. If it pairs two different matches, it creates a phantom sure bet in which both bets can lose.

Markets are the same problem. "Over 2.5 goals" is unambiguous. But "Handicap −1" can be a European handicap with three outcomes or an Asian handicap with two, and they settle differently (see Asian handicap). Where the data supplier already names events and markets consistently, as ours does, matching is more reliable. It is never perfect, so check briefly before every bet that the match, date and market agree at both bookmakers.

Normalising rules and fees

Two prices on the same question are only comparable if they settle under the same rules. Typical traps:

• Extra time: an ice hockey winner including overtime is not the same as 1X2 after 60 minutes (overtime rules).
• Tennis retirements: bookmakers settle a retirement differently (tennis retirement rules).
• Betting fees: if a bookmaker passes on Austria's 5% Wettgebühr, its real price is lower than the one shown (Austria betting tax).
• Exchange commission: an exchange deducts commission from net winnings (betting exchanges).

ArbVantage prices exchange commission into the effective odds and applies the Austrian and German betting fees per bookmaker and country, as far as we know how each bookmaker passes them on. Markets whose settlement rules differ in a way that matters are not paired, or carry a flag so you check the bet slip.

Latency: the real problem

Between a price at the bookmaker and your bet there is a chain of delays:

1. The bookmaker changes its price.
2. The data supplier notices the change on its next collection.
3. The scanner picks up the new data on its next request.
4. You see the opportunity, open both bookmakers and type.

Each step takes seconds to minutes. A sure bet in any software is therefore always a picture of the recent past. Good software tells you how old that picture is and throws away prices that are too old. ArbVantage discards quotes older than 20 minutes for events within three hours of the start, with longer limits for events further away. Within a market, a quote that lags more than five minutes behind the newest quote is dropped, so a bookmaker whose feed has stalled cannot form a leg. A fresh 2.5% ranks above a 3% that was last seen fifteen minutes ago.

In-play prices move even faster. Research on goals in football shows betting markets absorb new information within seconds (Croxson and Reade, 2014). That is why ArbVantage shows only pre-match sure bets; live arbitrage betting explains why in-play arbitrage is hard to do by hand.

Recognising false alarms

Not every sure bet a scanner shows is real. The most common causes:

• Pricing errors (palps): a bookmaker has mistyped, say 3.20 instead of 1.32. Such bets are often voided (voided bets and palpable errors).
• Stalled feeds: one bookmaker's price hasn't been refreshed for minutes and has long since changed.
• Wrong matching: two different events or markets treated as the same.
• Suspended markets: the bookmaker isn't taking bets right now, but the last price is still in the feed.

ArbVantage drops a bookmaker from a market when its margin-free price deviates by more than 10% from the market median. In thin markets without a sharp reference bookmaker, sure bets are capped at 4%. Anything above 15% is marked "check carefully" and ranked after every normal sure bet; above 30% it is dropped as implausible. That cuts false alarms; it does not eliminate them.

Why sure bets vanish so fast

A sure bet exists because one bookmaker prices an outcome differently from the rest of the market. It disappears when that gap closes, and that is often quick:

• The bookmaker corrects its price because others have moved or because money keeps arriving on one side.
• New information such as a line-up or an injury moves every price (dropping odds).
• The market is suspended or the maximum stake is reduced.

Research on arbitrage between bookmakers and exchanges finds such opportunities do exist but are small and short-lived (Franck, Verbeek and Nüesch, 2013). For you that means: act promptly, but always check each price at the bookmaker itself. If a price changes between your two bets, what to do when one leg fails walks through the options.

Coverage, honestly

No scanner covers every bookmaker. What matters is whether yours are included. Our current data supplier does not yet cover every bookmaker used in Austria and Slovakia; several local bookmakers are still missing from the feed. In the app you can see for each of your bookmakers whether it is covered, and sure bets are only calculated from the bookmakers you have added. For what to compare when choosing a tool, see best arbitrage betting software; the difference from a plain odds comparison site is in odds comparison vs arbitrage scanner. Value bets are not available in ArbVantage yet; they are coming soon.

FAQ

Where does arbitrage software get its odds?

Either from commercial data suppliers that deliver many bookmakers' prices through an API, or by reading bookmaker websites directly. ArbVantage takes its odds from a commercial odds data provider and stores, for every price, when it was last seen.

Why is a sure bet gone when I open the bookmaker?

Because time passes between the price in the software and your bet: the bookmaker changes its price, and the data supplier and the software only pick up the new price on their next update. Sure bets appear when one bookmaker is out of line and disappear as soon as it corrects.

Can arbitrage software show sure bets that are not real?

Yes. Causes include pricing errors that are later voided, stalled feeds, suspended markets and wrongly matched events. Good software filters stale prices and outliers, but you should check each price and market at the bookmaker before you confirm.

Does ArbVantage show live sure bets?

No. ArbVantage shows pre-match sure bets only, because in-play prices change faster than two bets can be placed by hand.

Sources

• Franck, E., Verbeek, E., Nüesch, S. (2013): Inter-market Arbitrage in Betting. Economica 80(318), 300–325
• Croxson, K., Reade, J. J. (2014): Information and Efficiency: Goal Arrival in Soccer Betting. The Economic Journal 124(575), 62–91
• Kaunitz, Zhong, Kreiner (2017): Beating the bookies with their own numbers, arXiv:1710.02824
• Wikipedia: Arbitrage betting

As of October 2026. The calculations are illustrations under the stated assumptions. Not betting, legal or tax advice. 18+.

Betting involves risk, sure bets included: odds move, bets get voided and accounts get limited. Only stake money you can afford to lose. If betting stops being fun, our responsible gambling page lists free help in Austria and Germany.