Arbitrage Calculator
When two venues price the same event differently enough, you can back every outcome and profit whichever way it lands. This arbitrage calculator works out exactly how much to stake on each side and what you are guaranteed to walk away with.
Enter the odds for every outcome, then type a stake on any one of them. The other stakes fill in automatically so that all outcomes return the same payout, which is what makes the profit locked rather than lucky. Total stake, total payout, and profit in both cash and percentage terms appear underneath.
The same tool handles hedging. If you already hold a position and the price on the other side has moved, put your original stake in that row and the calculator tells you what to lay against it to guarantee a result no matter what happens. The panel header shows the combined implied probability of the market. Anything under 100 percent is an arbitrage, and how far under it sits is your margin.
How to use this calculator
- Enter the odds for every outcome. Use the toggle for American, decimal, fractional, or percentage prices. Percent is the one to use for prediction markets, where a contract trading at 48 cents is simply 48 percent. Typing a price with a percent sign, a slash, or a decimal point switches the format on its own.
- Type a stake on one outcome. That row is marked FIXED and every other stake recalculates around it. Edit a different stake and the anchor moves there instead.
- Read the margin in the panel header. It is the profit percentage the market is offering before you decide how much to put through it. Below zero means no arbitrage exists.
- Check the payout column. Every row should show the same figure. That equality is the whole point, because it is what removes the outcome from the result.
- Place both sides quickly. The calculation is only valid while both prices are live, and arbitrage windows close in seconds rather than minutes.
How arbitrage is calculated
Convert each price to its implied probability and add them up. A market with no margin totals exactly 100 percent. A normal market totals more, and that excess is the bookmaker’s cut. Arbitrage is the rarer case where two independently priced venues combine to total less than 100 percent, which means the market as a whole is paying out more than it takes in.
The stake split
Call the combined implied probability A. Your total payout is total stake / A, and each outcome takes the share (1 / decimal odds) / A of your total stake. Because every stake is proportional to its own implied probability, all outcomes return the same amount, and the profit no longer depends on which one wins.
Your margin
Return on total stake is (1 / A) - 1. If the combined implied probability is 96.40 percent, you make 3.73 percent on everything you put through the market. Real arbitrage margins usually sit between 1 and 4 percent, so the profit comes from repetition and size rather than from any single position.
Note what happens if you use this to hedge a position you already hold. The stake figure it gives you for the other side is still correct, but the profit line treats both stakes as money you are putting up now. If your first stake is already committed and cannot be recovered, your real decision is only about the new stake, and the honest comparison is the guaranteed payout against what you would keep by leaving the position alone.
The hard part was never the arithmetic. It is finding two venues out of sync before the gap closes, and prediction markets have made that more common, because they reprice on order flow while sportsbooks reprice on a risk desk. The DG3 terminal is built around that gap, ranking markets by the distance between a no-vig sportsbook price and what prediction markets are showing. This calculator is what you reach for once you have found one.
Frequently asked questions
What is arbitrage betting?
Backing every outcome of an event across different venues at prices that combine to guarantee a profit. It works when the combined implied probability of all outcomes falls below 100 percent, which happens because each venue prices independently and they do not always agree.
How do I calculate the second stake?
Multiply your first stake by its decimal odds to get the payout you are targeting, then divide that payout by the decimal odds of the other outcome. That is the stake which makes both sides return the same amount. The calculator does this for you and extends it to markets with three or more outcomes.
What is a good arbitrage percentage?
Most genuine opportunities land between 1 and 4 percent. Anything above roughly 5 percent deserves a second look, because it usually means one of the prices is stale, the market rules differ between venues, or a line is about to be voided. Free money that looks too easy normally is.
What is the difference between arbitrage and hedging?
The arithmetic is identical. Arbitrage means opening both sides at once because the prices already guarantee a profit. Hedging means you already hold one side and are closing out the risk after the price has moved. The calculator handles both, since either way you are solving for the stake that equalises the payouts.
Why did my arbitrage disappear before I could place it?
Prices move constantly and the gap between two venues is exactly what each one is trying to correct. A window that exists when you load a page often closes within seconds. Getting the second leg down fast matters more than optimising the stake to the last unit.
What are the risks if the maths is guaranteed?
The arithmetic is certain, the execution is not. A leg can be rejected, a line can move between your two placements, and the two venues may settle a contested result differently, which leaves you holding one side instead of both. Sportsbooks also restrict accounts they identify as arbitraging. The guarantee only holds if both positions are actually filled and both settle the same way.