What is a betting exchange and how does commission work?
A betting exchange is a marketplace where bettors bet against each other instead of against a bookmaker. One user backs an outcome, another lays it, and the exchange matches the two and takes a commission out of the winner's profit on that market.
Team FootyMetrics
Updated Jul 2026 · 7 min read
- An exchange does not set its own odds or take the other side of your bet. It matches backers with layers and charges commission on the winner's net profit.
- Backing works exactly like a normal bet with a bookmaker. Laying is different: you win the backer's stake if the selection loses, and you pay out if it wins.
- A lay bet's risk is the liability, the backer's stake multiplied by (odds minus 1). Laying at odds of 3.00 against a £10 stake carries £20 of liability.
- Commission is charged on net winnings across a market, not on every stake, and never on a loss. That's a structural reason exchange prices often beat a bookmaker's on popular markets.
What a betting exchange is
A betting exchange is a marketplace, not a bookmaker. On a normal bookmaker site, every bet is placed against the house: the odds are set by the bookmaker, and the bookmaker pays out or keeps the stake depending on the result. On an exchange such as Betfair or Smarkets, bets are placed between users. One user backs a selection to win, another lays the same selection (bets it will not happen), and the exchange’s software matches the two when their prices line up. The exchange itself never takes a position on the outcome. It makes its money by charging commission on the winning side of a matched bet.
That structure is why exchange odds move differently to a bookmaker’s board. Prices are set by supply and demand between users rather than by a trading team pricing a match. If more people want to back a team, the price shortens. If more people want to lay it, the price drifts out.
Back and lay, the actual mechanic
Backing on an exchange is the bet you already know. You back a selection to win at the odds shown, and if it wins, you’re paid your stake back plus winnings at those odds. Lose, and you lose your stake. That side works the same as backing at any fixed-odds bookmaker.
Laying is the side that’s unique to exchanges. When you lay a selection, you’re betting it will not happen, and in doing so you’re effectively acting as the bookmaker for that one bet. Someone else backs the selection against you. If the selection loses, you keep their stake, minus commission on your win. If it wins, you have to pay them out at the odds you laid.
That second outcome is the part new users get wrong. A back bet can only lose the stake. A lay bet can require paying out far more than the stake you appeared to risk, because you’re on the hook for the backer’s winnings.
Working out liability
The amount a layer stands to lose is called liability, and it isn’t the same number as the stake. Liability is the backer’s stake multiplied by the lay odds minus 1.
Take a £10 backer’s stake at lay odds of 3.00. Liability is £10 multiplied by (3.00 minus 1), which is £10 multiplied by 2.00, so £20. If the selection loses, the layer keeps the £10 stake, minus commission on that profit. If it wins, the layer pays the backer £20.
| Backer’s stake | Lay odds | Liability if selection wins | Layer’s gain if selection loses |
|---|---|---|---|
| £10 | 2.00 | £10 | £10 (minus commission) |
| £10 | 3.00 | £20 | £10 (minus commission) |
| £10 | 5.00 | £40 | £10 (minus commission) |
The pattern is straightforward: the longer the lay odds, the bigger the liability relative to the stake being laid against, even though the potential gain if the bet loses stays capped at that stake. Exchanges hold the liability amount from a user’s account balance while the bet is open, so a layer can never lose more than they can already cover.
How commission actually works
This is the part that trips people up most: commission is charged on net winnings on a market, not as a flat percentage of every stake placed, and it is never charged on a loss.
Net winnings on a market means the exchange looks at overall profit across every bet placed on that market once it settles, not bet by bet. Someone who backed one selection and laid another in the same market and ended up with an overall profit pays commission on that net figure. Someone who lost overall pays no commission, because there is no profit to take a cut of.
A simple single-bet example: back a selection with a £10 stake at odds of 3.00. If it wins, the return is £30, which is £20 profit plus the £10 stake back. Commission is charged only on the £20 profit, not on the £30 return and not on the original £10 stake. At a 5% rate, that’s £1 in commission, leaving £19 profit plus the stake.
What Betfair actually charges
Why exchange prices are often better
A traditional bookmaker builds a margin, the overround, into every price on its board, on every outcome in the market, so the book turns a profit regardless of the result. See what fair odds are for how that margin works and how to strip it back out mathematically.
An exchange doesn’t need to bake a margin into the price itself, because it isn’t taking a side. Its revenue comes from commission on the winning side of matched bets, not from a spread built into the odds. That’s a structural reason exchange prices can run longer than a bookmaker’s on the same outcome, especially on popular, heavily traded markets like Premier League match odds or the correct-score market on a big fixture.
That is a tendency, not a rule. It does not mean every exchange price beats every bookmaker on every market, and it says nothing about which one wins on any given bet.
The liquidity catch
An exchange price is only real if someone else is willing to take the other side of it at that price. On a big Saturday Premier League match, that’s rarely a problem. There’s enough money moving through the market that most prices are backed by real, matched liquidity at reasonable size.
On a lower-tier market, a lower league fixture, a niche player prop, or a market close to kick-off when volume has already dried up, that liquidity can thin out fast. The best-looking price on screen might only be available for a small stake, with the next best price notably worse. A fixed-odds bookmaker doesn’t have that problem in the same way, since it prices and lays off its own risk rather than waiting for a matching user. An exchange isn’t automatically the better venue for every bet. It depends on whether the market has the depth to actually match your size at the price you want.
Betting exchange FAQs
Is a betting exchange the same as a bookmaker?
No. A bookmaker sets its own odds and bets against its customers. An exchange matches customers against each other and charges commission on the winning side, taking no position on the outcome itself.
What does laying a bet mean?
Laying means betting that a selection will not happen. The layer takes on the position a bookmaker normally holds for that one bet, collecting the backer's stake if the selection loses and paying out at the agreed odds if it wins.
How is liability calculated on a lay bet?
Liability is the backer's stake multiplied by the lay odds minus 1. Laying a £10 stake at odds of 3.00 carries £20 of liability, since £10 multiplied by (3.00 minus 1) is £20.
Does an exchange charge commission on losing bets?
No. Commission is charged only on net winnings on a settled market. A bet or market that loses overall has no commission taken from it.
Is Betfair's commission rate always 5%?
5% is the current market base rate quoted for UK customers, with a rewards structure that can move it to 2% or 8% depending on the package a customer has chosen. Rates and structures are set by the exchange and can change, so it's worth checking the exchange's own charges page for the current figure rather than treating any single number as fixed.