Arbitrage Calculator: Lock Guaranteed Profit Across Bookmakers (2026)
Type the prices two or more books are offering on the same market. If their combined margin drops below 100%, this splits your stake so every result pays the same and you bank a profit no matter who wins.
Stake mode
Set a budget and split it across every outcome.
Add at least two outcomes with valid odds.
Stake plan
Add at least two outcomes with valid odds to see the split.
Before you fire it in
Arbitrage is real but fragile. Prices move in seconds, books void mistaken odds, and accounts that only ever arb get limited fast. Stake what you can afford to have tied up, and double-check every line before you commit.
How the split works
Read the implied probability
Each decimal price is just 1 divided by itself as a percentage. Odds of 2.00 imply 50%.
Add them up
Sum the implied probabilities of the outcomes. Under 100% means the market is beatable.
Weight the stakes
Bigger probability gets a bigger slice, so every outcome returns the same money.
The math, plainly
Three lines do all the work.
Arbitrage check
Two prices of 2.10 give 0.476 + 0.476 = 0.952, under 1, so it is a sure bet.
Stake for each leg
On $1,000 that is $500 a side at 2.10, both returning $1,050.
Locked profit
$1,000 / 0.952 − $1,000 = $50, a 5% return whoever wins.
Arbitrage betting calculator: how sure bets really work
Arbitrage is the closest thing betting has to a free lunch, and like any free lunch it comes with strings. As of 2026 the prices that create arbs vanish in seconds and the accounts that chase them get watched. This guide walks through the math, the workflow, and the traps, so the number this calculator shows is a number you can actually collect.
What an arbitrage bet actually is
An arbitrage, or sure bet, exists when two or more bookmakers price the same event so differently that you can back every outcome and still come out ahead. The market only has to disagree by a little. If one book is high on the favourite and another is high on the underdog, the gap between them is your edge.
The signal is simple: convert every price to an implied probability, add them up, and if the total is under 100% you have found an arb. The calculator does this the moment you type, and the percentage it reports is the profit you keep on the money you put down.
The first arb I ever placed paid 3.2%. The second one I tried to place, the underdog price had already dropped by the time I switched tabs. That second non-bet taught me more than the first: speed is the whole game.
Why arbitrage stays small (and why that is fine)
Nobody retires on a single sure bet. The edge is thin on purpose, because the moment a price is wrong enough to matter, the market eats it. Here is what shapes the size of what you can take.
Margins are tight
Most arbs land between 1% and 5%. A 2% arb on a $500 stake is $10. It adds up over hundreds of bets, not over one.
Prices move fast
An arb is a momentary disagreement between books. Get all legs on quickly or the window shuts and you are left with a one-sided bet.
Limits arrive
Books spot pure arbers through betting patterns and stake sizing, then cut your maximum stake. Mixing in normal-looking bets buys you time.
Capital gets tied up
You need funds in several accounts at once. Money sitting in a book you cannot withdraw instantly is part of the cost.
How this calculator handles the math
Every price you type is converted to decimal odds first, whatever format you entered. From there the implied probability of each leg is one divided by its odds. The sum of those probabilities is the heart of the check: under 100% and you have an arb, over 100% and the bookmakers keep the difference.
Stakes are weighted so each outcome returns the same amount. The leg with the higher probability gets a larger stake, which is what makes the returns line up no matter who wins. The guaranteed profit is simply that common return minus everything you staked.
Two real-world wrinkles are built in. Exchange commission lowers your effective odds, so the math uses the after-commission price. And once you round stakes to whole units, the perfect balance breaks slightly, so the profit shown is recomputed from your actual rounded stakes, not the textbook figure.
Using the calculator step by step
It updates live, so you can paste odds straight off a screen and watch the plan form.
- 01
Pick your odds format
Decimal, American or fractional at the top. Type prices the way your book shows them.
- 02
Add every outcome
Two for a tennis match, three for a 1X2 football market, more for any market with extra results.
- 03
Enter the best price for each
Use the highest odds you can actually get on each outcome, ideally at different books.
- 04
Set your stake mode
A fixed budget, a profit target, or a stake you have already placed on one side.
- 05
Round and place
Round to tidy numbers if you like, check the worst-case profit still holds, then get the bets on.
Mistakes that turn a sure bet sour
Most failed arbs are not math errors. They are execution errors. These are the ones that cost real money.
Backing the slow leg last
Place the bet most likely to move first. If the long price is going to drop, get it down before you cover the favourite.
Ignoring max stake limits
If a book caps you below your planned stake, the whole split is off. Check limits before you commit the first leg.
Forgetting commission
An exchange arb that looks like 2% can be negative after 5% commission. Always enter the rate.
Trusting voided-odds protection
Books void obvious palpable errors. If one price looks too good, assume it might be pulled and you are left one-sided.
Chasing tiny edges
A 0.3% arb barely covers the risk of a price moving mid-placement. Set a floor and skip the marginal ones.
Arbing from one account
Every leg at the same book is not an arb, it is a graded single bet. Outcomes must sit at different operators.
Arbitrage terms, defined
The vocabulary you will meet on arbing forums and odds screens.
- Another name for an arbitrage: a set of bets that guarantees profit across every outcome.
- The chance a price implies, found as one divided by the decimal odds. Odds of 4.00 imply 25%.
- How far the combined implied probabilities sit above 100%. It is the bookmaker's built-in edge.
- One of the individual bets that make up the arbitrage, one per outcome.
- Betting on an outcome NOT to happen, usually on an exchange. Pairs with a back bet for matched and exchange arbs.
- The cut an exchange takes from net winnings, which lowers your effective odds.
- When a bookmaker restricts an account, cutting stakes or removing promotions, often aimed at arbers.
- A single price that beats its true probability. Not a guaranteed win, but profitable over time.
Sure bet
Implied probability
Overround / margin
Leg
Lay
Commission
Gubbing / limiting
Value bet
Calculators that pair with this one
Arbitrage rarely lives alone. These tools cover the jobs around it.
Bet responsibly
Arbitrage ties up real money and the edge is small. Never stake funds you need, treat every figure as time-sensitive, and if betting stops being math and starts being a chase, get support at BeGambleAware.org.
Evgeniy Volkov
Verified ExpertFullstack developer with a background in mathematics. I build the calculators and game-style tools on ToolsGambling with Pixi.js and modern web tech, and every result uses transparent probability formulas you can verify yourself.