Arbitrage Calculator: Lock In Guaranteed Profit

An arbitrage bet, or surebet, turns two mismatched bookmaker prices into a locked profit. The maths is simple, but the execution is unforgiving. Stake the wrong amount on one side and your guaranteed return quietly becomes a guaranteed loss.

This arbitrage calculator removes the guesswork. Enter the odds on each outcome and set your total stake. It returns the exact amount to place on every side, so your profit stays identical whichever result lands. It handles two-way markets, three-way markets, and exchange lays with commission.

Below the tool you will find how the calculation works, worked examples with real numbers, the mistakes that erase arb profit, and an honest comparison with value betting. Arbitrage is real, but it burns soft bookmaker accounts fast, and that trade-off deserves a straight answer.

See how our surebets scanner finds live arbs across bookmakers in real time, so you are not refreshing prices by hand.

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The calculator runs one core check, then splits your stake. First it converts each price into an implied probability. In decimal odds, implied probability is 1 divided by the odds. A price of 2.10 implies 0.476, or 47.6 percent.

Next it adds the implied probabilities for every outcome of the market. This sum is the total book. When the total book falls below 1.00, or below 100 percent, an arbitrage exists and a profit is available.

When the total book sits above 1.00, the bookmakers' combined margin swallows the gap and no risk-free profit exists. The calculator tells you this plainly rather than pushing you into a losing position.

Stake splitting and the arb formula

Once an arb is confirmed, the tool distributes your total stake so each outcome returns the same payout. The stake on any outcome equals your total stake times that outcome's implied probability, divided by the total book.

That balancing is the whole point. A rough guess at the split leaves you exposed. One result pays well, the other pays under your combined outlay. The calculator locks both payouts to the same figure, which is what makes the profit certain.

The profit percentage is straightforward too. It equals 1 divided by the total book, minus 1, expressed as a percent. A total book of 0.96 returns roughly 4.2 percent before commission and rounding.

Odds formats and exchange commission

Enter decimal, fractional, or American odds. Decimal is cleanest for arbitrage because implied probability is a direct reciprocal, with no conversion step to get wrong under time pressure.

If one leg is a lay on an exchange such as Betfair or Smarkets, commission changes the real return. A 2 percent commission on winnings trims your edge, so the calculator adjusts the lay stake and the profit line to reflect the true net figure, not the gross one.

Reading the output

A clean result gives you three things: the stake for each outcome, the identical payout each stake returns, and the profit as an absolute figure and a percentage. Check that both payouts match before you place anything.

If the profit line is negative, there is no arb at those prices, and the tool is telling you to walk away. If it is positive but tiny, weigh it against rounding and the risk that one leg moves before you fill it.

What the tool cannot see

The calculator works from the numbers you give it. It does not know a soft book's real maximum stake, the live exchange liquidity, or whether a price is a genuine offer or an error about to be voided.

Treat its output as a correct staking plan, not a promise the market will honour. The sections below cover the execution risks that sit outside the maths.

Arbitrage exists because bookmakers set prices independently. A soft book shading a line toward public opinion can drift out of step with a sharp book like Pinnacle. When two operators disagree enough, backing every outcome guarantees profit.

The term surebet describes the same thing. Arbers, arbitrage, surebets, and sure wins all point to one idea. Cover every result across different books so the combined implied probability is under 100 percent. Our surebet calculator serves the same maths under the term UK bettors search most.

Where the edge comes from

The edge is priced inefficiency, not prediction. You are not forecasting the result. You are exploiting the moment two operators publish contradictory prices before one of them corrects.

That window is short. Sharp books move fast, and soft books limit or void obvious errors. Most clean arbs live for seconds to a few minutes, which is why manual scanning across fifty markets rarely keeps pace.

Two-way and three-way markets

A two-way market has two outcomes, such as a tennis match with no draw. These arbs are the most common and the easiest to fill, since you only chase two prices before they move.

A three-way market adds a draw, as in football match result betting. Three-way arbs are rarer and tighter, because you need three books to disagree at once, and rounding across three stakes eats more of a thin margin.

Realistic returns and volume

Individual arbs are small. Value betting literature and public arbitrage data put typical margins around 1 to 5 percent per opportunity, with most clustered at the low end after commission and rounding.

Profit comes from turnover, not from any single bet. Placing many small arbs compounds a thin edge into a meaningful return, provided your accounts survive long enough to keep firing. That survival is the real constraint, covered below.

For a fuller conceptual breakdown of the strategy, see our guide to arbitrage in betting, which sits alongside this tool.

Numbers make the mechanic concrete. Each example below assumes a total stake and shows the split the calculator produces, so you can sanity-check the tool against your own inputs.

Two-way market, tennis

Player A is 2.10 at one soft book. Player B is 2.05 at another. Implied probabilities are 0.476 and 0.488, a total book of 0.964. That 3.6 percent gap is your arb.

On a 1,000 unit total stake, the calculator places about 507 on Player A and about 493 on Player B. Both sides return roughly 1,037, a locked profit near 37 units whichever player wins.

Three-way market, football

A match result market splits across home, draw, and away. Suppose home is 2.70, draw is 3.60, away is 3.10, each at a different book. Implied probabilities sum to 0.987, a thin 1.3 percent edge.

The calculator distributes your stake across all three outcomes so every result pays the same. Three-way arbs are tighter and rarer. Rounding to whole units eats more of the margin, so the tool flags when a split is too thin to survive rounding.

Back and lay on an exchange

Here you back an outcome at a soft book and lay the same outcome on an exchange. The calculator needs the back odds, the lay odds, and the exchange commission to compute the lay stake and liability.

Say you back at 3.40 and lay at 3.50 with 2 percent commission. Without the commission the arb looks clean. With it applied, the calculator shows the real net profit, which is smaller, and confirms whether the position still clears.

A low-stake starter

New arbers often start at 50 or 100 units to learn the workflow. On a 3 percent arb, a 100 unit total stake nets about 3 units. That looks trivial, but the goal at this stage is clean execution, not profit.

Get both legs placed at the shown prices, ten times in a row, before you scale the stake. Speed and accuracy are the skills that pay later; the early bets are practice with real money on the line.

A mid-volume profile

Consider a bettor with six soft accounts and a Betfair account, running 200 to 300 units per arb across football and tennis. Their edge per bet averages around 2.5 percent, thin but consistent.

Over a busy weekend they might place 40 arbs. At that stake and margin, the maths points to a few hundred units of profit, before any account gets limited. Their real skill is not the calculator; it is filling both legs fast and keeping each account looking ordinary.

This profile also shows why turnover, not stake size, drives the return. Doubling the number of clean arbs matters far more than chasing a slightly fatter margin on any single one.

A weighted variation

Some bettors overweight the outcome they judge likelier, accepting a small loss on the other side for a larger win if their read is correct. This is no longer risk-free, and it is a different bet.

Treat weighted arbing as a value play, not a surebet. If you want to spread stake across several selections in one event rather than cover a two-way arb, the dutching calculator is the right tool.

Before software, arbers found opportunities by comparing prices across books manually. Understanding that process helps you sanity-check any tool, and it explains why speed matters so much once you scale.

Converting the three odds formats

Decimal odds show the total return per unit staked. Fractional odds show profit relative to stake, so 6/4 equals 2.50 decimal. American odds use a baseline of 100, where minus figures show the stake needed to win 100, and plus figures show the profit on a 100 stake.

For arbitrage, convert everything to decimal first. Implied probability then becomes a clean reciprocal, and comparing books across formats stops introducing conversion errors when you are moving fast.

Spotting the gap

Take the best available price for each outcome, from any book. Convert each to implied probability, then add them. If the sum lands under 1.00, an arb exists at those prices, at that moment.

Doing this by hand across two books and one market is manageable. Doing it across fifty markets and a dozen books, fast enough to place before prices move, is not. That gap is exactly what a scanner closes.

Why devigging matters here

Sharp books like Pinnacle carry a low margin, so their devigged price sits close to the true probability. A soft book with a fatter margin and a shaded line is where the mispricing usually hides.

An arb is really two margins failing to overlap. When you understand each book's vig, you see why arbs cluster on certain markets and books, and you learn where to point your attention first.

Most blown arbs are execution errors, not maths errors. The calculator handles the maths. These are the failures it cannot catch for you.

Placing one leg, then losing the other

You back the first side, switch tabs, and the second price has already moved. Now you are exposed on a single outcome with no cover. Confirm both legs are available and near your entry price before you stake anything.

Ignoring the maximum stake

Soft books cap stakes on shaded markets, and exchanges have limited liquidity. A perfect arb is useless if you can only get 20 units on one side of a 500 unit plan. Check the real available stake, not the theoretical one.

Forgetting exchange commission

An arb that looks profitable on gross odds can be a loss once commission applies to the lay winnings. Always enter the commission. A 2 to 5 percent charge routinely flips a marginal arb negative.

Chasing palpable errors

A price that looks too good is often a palpable error, and bookmaker terms let operators void those bets. You place both legs, the obvious one gets voided, and you are left holding a naked position. Treat outlier prices with suspicion.

Rounding stakes the lazy way

Rounding both stakes up or down without rechecking the split can skew your payouts. One outcome ends up paying more than the other, which reintroduces the risk you were trying to remove. Let the calculator round, then verify both payouts still match.

Betting into your own restriction

Aggressive, rounded, arb-shaped stakes are a signature bookmakers watch for. Fire enough of them and accounts get limited or closed, a reality we cover in how to avoid bookmaker limitation. Stake sizing that mimics a recreational bettor lasts longer.

Arbitrage and value betting solve the same problem, beating the closing line, with opposite risk profiles. Knowing which fits your situation matters more than the odd extra percent.

Arbitrage locks profit instantly and carries no variance on a clean arb. The cost is speed. Obvious, rounded, two-sided stakes flag your account quickly, and soft books restrict arbers faster than almost any other player type.

Value betting accepts short-term variance in exchange for account longevity. You place single +EV bets that look like ordinary punts, so a soft book tolerates you longer. Over thousands of bets, positive expected value and strong closing line value carry the return.

Speed versus longevity

An arb pays today and risks your account tomorrow. A value bet risks a losing run today and protects your account for the long haul. Neither is strictly better; they suit different stages and different bankrolls.

Closing line value ties the two together. Both approaches aim to beat the price the market settles at. A Bet Tracker that logs CLV tells you whether either is actually working, well before your profit and loss confirms it.

Which one for your context

For a bettor with fresh accounts and small volume, arbitrage builds a bankroll fast before restrictions bite. For a bettor targeting 500 or more bets a month and long account life, value betting scales better and draws less heat.

Many sharp bettors run both. They arb while an account is fresh, then shift toward +EV as it matures. Our value betting hub explains that transition, and the same Bet Tracker logs CLV across both approaches.

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Is arbitrage betting legal?

In most regulated markets, arbitrage betting itself is legal. You are placing standard bets on licensed operators. The catch is contractual, not criminal. Bookmaker terms allow operators to limit or close accounts they judge to be arbing, and that is a business decision on their side, not a law on yours.

Does the calculator guarantee I make money?

The maths guarantees an equal payout across outcomes when the total book is under 100 percent. It cannot guarantee execution. Prices move, stakes get capped, legs get voided, and commission bites. The calculator gives you a correct plan; whether the market lets you complete it is a separate risk.

Why do my arb profits look so small?

Clean arbs typically return 1 to 5 percent, and most sit near the bottom of that range after commission and rounding. Arbitrage is a volume game, not a jackpot. Profit accumulates across many small, fast bets, which is why manual scanning rarely keeps up with the opportunities.

How is a surebet different from an arbitrage?

They are the same thing. Surebet is the term UK and European bettors search most; arbitrage is the more technical label. Both mean covering every outcome across different books so the combined implied probability falls under 100 percent, locking a profit regardless of the result.

Will arbing get my bookmaker account restricted?

Often, yes. Rounded stakes, two-sided betting, and repeated action on shaded markets are patterns soft books watch for. Many arbers see accounts limited within tens to hundreds of bets. Varying stake sizes and avoiding obvious arb shapes extends account life, but restriction is a known cost of the strategy.

Can I arb using a betting exchange?

Yes, and many arbs pair a soft book back with an exchange lay. You must enter the exchange commission, usually 2 to 5 percent, because it applies to your winnings and reduces the real edge. Exchange liquidity also limits how much you can actually get matched at the shown price.

What bankroll do I need to start arbing?

There is no fixed figure, but your bankroll must be split across several bookmaker and exchange accounts at once, since both legs are staked simultaneously. Many bettors start with enough to cover 20 to 30 units per side comfortably. Spread across accounts, a few hundred units is a realistic entry point.

Use the tool above to size every arb correctly, respect the account-restriction risk, and treat value betting as the longer game once your accounts mature.

One last point worth stating plainly. Arbitrage removes result risk on a single position, but it does not remove the risks that come with betting itself. Stake only what you can afford, keep records, and step back if the activity stops feeling like a numbers exercise. The maths is neutral; how you use it is not.