Arbitrage calculator.
An arbitrage bet, or sure bet, covers every outcome of an event across different bookmakers so that whatever happens, you come out ahead. Enter the best odds you can find for each outcome and your total stake, and this free calculator tells you whether an arb exists, exactly how much to stake on each side, and the profit you lock in. It handles two-way and three-way markets.
Find the sure bet
LiveProfit margin
5.00%
guaranteed profit 5.00
A positive margin is an arb: stake as shown and every outcome returns the same. A negative margin means no arb at these odds. Calculations run in your browser; nothing is stored. For entertainment, not betting advice.
The short answer
What is arbitrage betting (a sure bet)?
Arbitrage betting, also called a sure bet or arb, means backing every outcome of an event at different bookmakers whose odds disagree, so that the combined prices guarantee a profit no matter the result. It exists because bookmakers price events differently, and occasionally their best odds leave a gap you can exploit.
How to use this calculator
Enter the best odds you can find for each outcome, ideally from different bookmakers, and your total stake. For a two-way market leave the third box blank; for a three-way market like football 1X2, fill all three. The calculator works out whether the odds form an arb, the exact stake for each outcome, and the guaranteed profit.
If the profit margin is positive, you have a sure bet: split your stake as shown and every result returns the same amount, locking in that profit. If it is negative, the odds do not cover all outcomes and there is no arb to be had.
The formula
No black box.
Here is the math.
Add up the implied probabilities. If they come to less than 100%, the gap is your arb.
# Arb exists if (total < 1)
total = 1/odds₁ + 1/odds₂ (+ 1/odds₃)
# Profit margin
margin = (1 / total) − 1
# Stake per outcome (total stake S)
stakeₕ = S × (1/oddsₕ) / total
# Every outcome returns
return = S / totalWorked through
A two-way arbitrage.
Say one bookmaker has outcome A at 2.05 and another has outcome B at 2.10. Different books, opposite sides.
Add the implied probabilities: 1 divided by 2.05 is 0.488, and 1 divided by 2.10 is 0.476. Together that is 0.964, or 96.4%. Because it is below 100%, the 3.6% gap is your arbitrage margin, a guaranteed 3.73% profit on the stake.
Split a 100 stake in proportion: 50.60 on A and 49.40 on B. If A wins you get 50.60 times 2.05, which is 103.73. If B wins you get 49.40 times 2.10, also 103.73. Either way you turn 100 into 103.73, a 3.73 profit locked in before the event even starts.
That is the whole idea: the two prices, taken from different bookmakers, between them cover both outcomes for less than the true 100%, and the difference is yours.
Three outcomes
A three-way (1X2) example.
Football has three results, home, draw and away, so an arb has to cover all three. The maths is the same, just with one more term.
Take home at 3.50, the draw at 3.60 and away at 2.40, each the best price from a different book. The implied probabilities are 0.286, 0.278 and 0.417, which add to 0.980, or 98%. That 2% gap is the arb.
On a 100 stake, that splits to 29.15 on the home, 28.34 on the draw and 42.51 on the away. Whichever result lands, you collect about 102.02 for a 2.02 profit. Three-way arbs are rarer and tighter than two-way ones, because three prices have to line up instead of two.
A reality check
How big are arbitrage profits?
Smaller than the hype suggests. Most genuine arbs are tiny, and the big ones are usually a trap.
Real arbitrage margins are typically 1% to 5%, and most sit under 2%. To make meaningful money you need either large stakes or a high volume of bets, both of which draw attention fast. On a 2% arb, a 100 stake makes 2; you would need to turn over 5,000 across an event to make 100.
Be very suspicious of large arbs. A 10% or 20% “sure bet” almost always means one bookmaker has made a pricing error they will void, or you have misread a market, for example a different handicap line or a player-specific rule. If an arb looks too good, it is usually because it is not real.
Finding them
How to find arbitrage bets.
Arbs come from bookmakers disagreeing on a price. Spotting them is a matter of comparing odds quickly and widely.
The raw method is to compare the best available odds for each outcome across many bookmakers, then drop them into this calculator to see if the total dips below 100%. Odds-comparison sites help, and dedicated arb scanners automate the search across dozens of books, though the good ones charge a subscription.
Arbs appear when a bookmaker is slow to move a price, prices a niche market loosely, or pushes a generous promotion. They also vanish quickly: as soon as money flows in, the odds shorten and the gap closes, often within minutes. Speed and having accounts ready at several books is most of the game.
The clock
How long do arbs last?
Usually not long. The short shelf life of an arbitrage is the single biggest practical challenge after account limits.
An opportunity appears when one bookmaker is slow to react or runs a generous price, money flows toward the mispriced side, and the odds shorten until the gap closes, often within a few minutes on popular pre-match markets. In-play arbs are faster still and can vanish in seconds as prices update live.
That short window shapes how arbing actually works. You cannot leisurely place both legs: you need accounts already funded at several bookmakers and an exchange, the stakes worked out in advance, and the speed to get both bets on before the price moves. It is why serious arbers lean on scanners and keep a float spread across many accounts, and why a calculator like this one earns its keep, since you confirm the arb and the exact stake split in seconds rather than minutes.
Read this first
Why “risk-free” is not risk-free.
The maths of an arb is guaranteed. Actually collecting it, repeatedly, is where the real risks live, and no calculator can remove them.
Account limits and bans. This is the big one. Bookmakers spot arbitrage quickly, from the odd stake sizes and a habit of only taking overpriced lines, and they respond by cutting your maximum stake to pennies or closing your account. Most arbers get limited at a given book within days or weeks, which is the real ceiling on this as an income.
Odds moving between legs. You place one side, then go to place the other and the price has shortened or gone. Now you are holding a one-sided bet that may no longer be an arb, and could be a straight loss. Both legs have to go on fast, and that is not always possible.
Stake limits. The book offering the value price may only accept a fraction of the stake you need, leaving your position unbalanced and the guarantee broken.
Voided and cancelled bets. If one leg is voided, settled under a different rule, or cancelled as a palpable pricing error, you are left exposed on the other side. The “sure” part assumes both bets stand exactly as placed.
Know the difference
Arbitrage vs matched betting vs value betting.
Three strategies that get muddled together. They are related, but the risk and the source of profit are different in each.
Arbitrage
Profit comes from bookmakers disagreeing on a price. You cover every outcome with your own money and lock in a small guaranteed margin. No free bet is involved, and the edge is the pricing gap itself.
Matched betting
Profit comes from bookmaker promotions, mainly free bets. You back and lay to cancel the risk, taking a tiny qualifying loss to unlock a free bet you then convert to cash. The edge is the offer, not the odds.
Value betting
Profit comes from betting only when your estimate of the chance beats the price, and being right more often than the odds imply. It is not risk-free at all: single bets can lose, and the edge only shows over a large sample.
In short: arbitrage and matched betting aim for near-certain small gains and get your accounts limited quickly; value betting carries real risk on each bet but is the only one of the three that bookmakers cannot simply switch off. Many bettors start with matched betting, move to arbitrage, and graduate to value betting.
Same thing
Arbitrage, sure bet or arb?
Different words, one concept: a set of bets across all outcomes that guarantees a profit.
Arbitrage (or arb)
The technical term, borrowed from finance, where you exploit a price difference between two markets for a risk-free gain. In betting, the two markets are two bookmakers.
Sure bet (or surebet)
The everyday name for the same thing, common in Europe. A sure bet and an arbitrage bet are identical, and this calculator works for both, however you say it.
The shared idea
Cover every result for a combined cost below 100%, stake each side in proportion, and the difference is locked-in profit. The names change with the country, the maths does not.
Book vs exchange
Back-and-lay arbitrage.
You do not always need two bookmakers. An arb can sit between a bookmaker and a betting exchange when the back price beats the lay price after commission.
Say you back 100 at 2.10 with a bookmaker and lay the same outcome on an exchange at 2.05, where commission is 2%. To balance, you lay about 103.45, which ties up 108.62 of liability in your exchange account. Whichever way it goes, you come out about 1.38 ahead, a 1.38% arb, because the back price you took is higher than the price you laid at.
This is the same back-and-lay split used in matched betting, with one difference: here both prices are real money rather than a free bet, so the profit is the pricing gap minus commission. Always include the exchange commission, because on margins this thin it can be the difference between an arb and a small loss.
Before you bet
An honest word on arbing.
Arbitrage is legal and, on paper, the closest thing to free money in betting. In practice it is a grind: small margins, large stakes tied up across many accounts, constant speed, and a clock ticking on every account before it gets limited. It can work, but it is a side hustle with a short shelf life per bookmaker, not a money printer.
Use this calculator to confirm an arb is real and to size both sides correctly before you place anything, and double-check the markets match exactly. Only ever bet money you can afford to lose, and if betting stops being fun or feels out of control, free confidential help is at BeGambleAware.org.
Questions
Arbitrage questions.
What is arbitrage betting?
+
Arbitrage betting means backing every outcome of an event at different bookmakers whose odds disagree, so the combined prices guarantee a profit whatever the result. It works because bookmakers price events differently, and occasionally their best odds leave a gap below 100% that you can exploit.
What is a sure bet?
+
A sure bet is just another name for an arbitrage bet, common in Europe and also written surebet. It is the same idea: a set of bets across all outcomes, placed so that you make a guaranteed profit no matter what happens. This calculator works for both terms.
Is arbitrage betting legal?
+
Yes, arbitrage betting is legal. You are placing normal bets at licensed bookmakers. However, bookmakers do not welcome it, and their terms allow them to limit or close accounts they believe are arbing. It is legal, but the books are within their rights to stop serving you.
Is arbitrage betting really risk-free?
+
The maths is risk-free, but collecting it is not. Odds can move before you place the second leg, a book may limit your stake or void a bet, and accounts get restricted for arbing. Done carefully it is low-risk, but the practical risks are real, not zero.
How much profit does arbitrage make?
+
Most genuine arbs are 1% to 5%, often under 2%. A 2% arb makes 2 on a 100 stake, so meaningful returns need large stakes or high volume. Very large arbs are usually a pricing error that will be voided or a misread market, not real profit.
How do I find arbitrage bets?
+
Compare the best odds for each outcome across many bookmakers and check whether the implied probabilities total below 100%. Odds-comparison sites help, and arb scanners automate the search across dozens of books for a subscription. Arbs vanish fast, so speed and ready accounts matter.
Will I get my account limited for arbing?
+
Very likely, in time. Bookmakers detect arbitrage from odd stake sizes and a pattern of only backing overpriced lines, and they respond by cutting your maximum stake or closing the account. Most arbers get limited at any given book within days or weeks, which is the main practical limit on arbing.
What is the arbitrage formula?
+
Add 1 divided by each outcome’s decimal odds. If the total is below 1 there is an arb, and the margin is 1 divided by that total, minus 1. Stake each outcome in proportion to its 1-over-odds share of the total, and every result returns the same amount.
Can you arb on a betting exchange?
+
Yes. You can arb between a bookmaker and an exchange, or between exchanges, by backing at one and laying at another when the prices line up. Remember to account for exchange commission on winnings, as it eats into a margin that is already thin.
Do arbitrage opportunities still exist?
+
Yes, but they are fewer and shorter-lived than years ago. Bookmakers price faster and limit arbers quickly, so arbs now tend to last minutes and to be small or on niche markets. They still appear across the market constantly; the challenge is catching and placing them before they vanish.
Can I do arbitrage with a small bankroll?
+
You can, but the cash returns are small. A 1% to 2% margin on small stakes earns pennies per bet, and you need funds spread across several bookmaker and exchange accounts to act on opportunities. Arbing rewards volume and speed far more than a single large bankroll.
Is arbitrage betting worth it?
+
It depends on your goal. Arbitrage can produce steady small profits, but the margins are thin, the work is constant, and bookmakers limit arbers within weeks, capping how long it lasts at any one book. For most people it is a modest side income at best, not a replacement for a job. Treat it as a low-risk hobby rather than a path to wealth.
What is the difference between arbitrage and value betting?
+
Arbitrage covers every outcome for a guaranteed small profit regardless of the result. Value betting backs a single outcome only when you believe its true chance beats the odds, and accepts that any one bet can lose. Arbitrage is near risk-free but quickly limited; value betting carries real variance but cannot be switched off by the bookmaker.
Can arbitrage betting be automated?
+
Partly. Scanners find arbs and alert you in real time, and some tools help size the stakes, but actually placing the bets is usually manual because bookmakers block automated betting. Full automation also raises the risk of fast account limits, so most arbers still place each leg by hand.
About the developer
Jean Borg
Jean builds and maintains every calculator on freecalculators.pro from Malta, with a focus on tools that are fast, free and show their working. This arbitrage calculator uses the standard implied-probability method and the figures are verified for accuracy. It is provided for education, not as betting or financial advice. Please bet responsibly. Page last updated June 2026.