What Is a Surebet? How a Price Gap Pays Either Way

Short answer: A surebet is a set of prices on the same match, taken from different bookmakers, that pays out more than you staked whichever side wins. One book offers 2.10 on the home side, another offers 2.05 on the away side, and a stake of 1,000 split between them the right way returns about 1,037 either way.

One stake, two books, the same return

The trick is in the split. Put the same amount on both sides and one result pays more than the other, so you would still be hoping for a particular winner. Stake a little more on the shorter price and a little less on the longer one, and the two returns meet in the middle.

In the example that means slightly under half of the money on the home side and slightly over half on the away side: 493.98 against 506.02. Whichever side wins, the winning ticket pays about 1,037, a margin of roughly 3.7 percent on the money that went in.

The same split works for any number of outcomes. Turn each price into a percentage by dividing one by the odds. If the percentages for every outcome add up to less than a hundred, the prices leave a gap, and each outcome gets a share of the stake in proportion to its percentage.

Why surebets exist

A single bookmaker never offers one. Every book builds a margin into its prices, so the percentages on its own market always add up to a little more than a hundred. That margin is the vig, and it is the reason backing both sides at one book loses money every time.

A surebet appears when two books disagree about the same match by more than their combined margins. One rates the home side more highly, the other rates the away side more highly, and each is pricing its own opinion. Put the best price for each side together and, if the disagreement is big enough, it outweighs both margins and a gap opens. Pinnacle, a bookmaker that competes on price, describes the condition the same way: enough difference of opinion between bookmakers, and the smaller their margins, the less disagreement it takes.

Three things have to line up at the same time:

• Two books that disagree about the same market, not two books describing two different markets with similar names.
• Margins small enough that the disagreement shows through. Two books each keeping eight percent rarely leave anything between them.
• Every outcome covered. A match that can be drawn needs the draw priced as well, or the two visible prices are not a complete set.

The vig calculator shows how much margin a book has built into any market you type in, which is a fair guide to how often that book will be one side of a surebet.

Why the margin is so small

The gap is what is left after two margins have been paid. The tightest books keep a couple of percent on a big football market, so two of them have to disagree by more than both cuts before a gap opens at all, and even then it is a few percent of the total stake at best.

Whatever is left is shaved again before it reaches you. An exchange takes a commission on winnings, stakes are rounded to whole cents, and two accounts in two currencies pay a conversion spread each way. None of these is large on its own; together they can take a three percent margin down to nothing, which is why you work out a surebet from the accepted prices after every cost, not from the numbers on the screen.

A gap that looks large is a warning rather than a gift. It usually means one price is stale, or that the two tickets do not settle the same way.

Where the margin dies before it locks

Between finding two prices and holding two accepted tickets there are four places where a surebet stops being one. Three of them cost money. The fourth only shrinks the margin.

• Rules differ. A retirement, a postponement or extra time is settled one way by the first book and another way by the second. One leg is voided, the other stands, and you are holding a plain bet you never meant to make.
• Second leg capped. The first book takes your full stake, the second accepts a fraction of what you asked for, and the split never completes.
• Price gone. The second price moves before the second ticket is placed. At the new price the gap may be gone, or negative.
• Partial fill. On an exchange only part of the stake is matched at the price you wanted. The rest is matched lower, or not at all, and the margin shrinks with it.

The risk is lopsided. In the example, one voided leg leaves almost 500 riding on a single result to protect a margin of about 37, which is why the rule and limit checks come before any money goes on.

Surebet, value bet, dutching and matched betting

Four things get called a sure thing, and they make different promises. Only one of them covers every outcome at prices that pay out more than the total stake.

A value bet backs one side you believe is priced too long, and it loses in the ordinary way when that side loses. Dutching spreads a stake across several outcomes so that each pays the same, but leaves at least one outcome uncovered, so it is a value bet with the risk spread around. Matched betting uses a bookmaker's promotion as the edge and an exchange to cancel out the result, which is why it sits closer to a surebet than to a prediction; our matched betting and arbitrage comparison goes through the differences. Calling a selective dutch a surebet, or a confident prediction a sure thing, is the habit that gives the word a bad name.

What to do next

If you want to try one, the order of operations matters more than the arithmetic, which the tool does for you.

1. Compare the best price on each outcome of the same complete market across the books you hold accounts with. A three-way market needs three prices.
2. Open the rules on both markets and check that a retirement, a postponement, extra time or a dead heat settles the same way on both tickets.
3. Check the maximum stake on each side before you place anything, and plan the split around the smaller one.
4. Enter the prices and your total stake in the surebet calculator. It returns the split, the return on each side and the margin, and it handles three or more outcomes and exchange commission.
5. Place the leg with the tighter limit first, check the other price again, then place the second leg using the amount the first book actually accepted.

Finding the gaps by hand is slow, and most people who do this regularly pay for a scanner that compares prices for them. A scanner result is still only a candidate until you have done the checks above yourself; our guide to free arbitrage software covers what the free tiers show and what they leave out.

Frequently asked questions