Guide · 5 min read
Back and lay bets explained
A back bet says something will happen; a lay bet says it will not. Lay bets need a betting exchange, carry a liability that can be several times the stake, and are practically unavailable to residents of Austria and Slovakia. This guide covers the maths and the back/back alternative.
Updated 22 October 2026
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Back and lay
At an ordinary bookmaker you always place a back bet: you bet that something will happen, for example "Sturm Graz win". The bookmaker takes the other side.
With a lay bet, you are the other side. You bet that the result will not happen. If Sturm do not win (draw or defeat), you win. If Sturm win, you pay the backer's winnings.
Lay bets are mainly offered on betting exchanges, where customers bet against each other. The exchange only matches the bets and charges a commission.
Lay liability
When you lay, you set the backer's stake (the "lay stake") and the odds. If you lose, you pay the backer's profit. That amount is your liability, and the exchange reserves it in your account straight away:
liability = lay stake × (lay odds − 1)
- Liability: €50 × (3.20 − 1) = €50 × 2.20 = €110.
- The result does not happen: you win the €50 lay stake, minus commission.
- The result happens: you lose the €110 liability.
At high odds the liability grows fast: a €50 lay at 11.00 has a liability of €500. That is why laying outsiders ties up a lot of money.
Some exchanges let you enter the liability instead of the lay stake. Then you work backwards: lay stake = liability ÷ (lay odds − 1). €110 of liability at 3.20 gives €50 again. Check which field you are filling in before you confirm; at odds of 11.00 a mix-up costs ten times as much.
Odds of 3.20 imply a probability of 1/3.20 ≈ 31.3%. At that probability the lay is fair before commission: 68.7% × €50 − 31.3% × €110 ≈ 0.
Commission
Exchanges do not earn from a margin built into the odds. They charge commission on your net winnings in each market. If you lose in a market, you pay none. Each exchange sets its own rate, often depending on the market and your turnover; a few percent is typical.
With an assumed commission of 5%, the lay above pays €50 × 0.95 = €47.50 when it wins. The €110 liability stays the same when it loses, because there is no commission on losses. Commission therefore shifts the break-even lay price: a lay only works out when the lay odds sit below the back odds you get at the bookmaker by more than the commission costs.
Laying without an exchange: back/back
Laying "Sturm win" is the same as backing "Sturm do not win", which is double chance X2. Instead of laying on an exchange, you can back the other side at a second bookmaker. This back/back hedge is the normal approach in countries without an exchange, and it is the basis of every sure bet.
Before commission, lay odds L correspond to back odds on the other side of:
equivalent back odds = L ÷ (L − 1)
3.20 ÷ 2.20 ≈ 1.455. A €110 back on X2 at 1.455 reproduces the lay exactly: if Sturm win, you lose €110. If Sturm do not win, you win €110 × 0.455 = €50.
If the bookmaker only offers X2 at 1.40, the same stake wins €44 instead of €50. The lay with 5% commission pays €47.50. Back/back is €3.50 worse here, but it is available in Austria.
Whether back/back is "as good" depends only on the prices. If a second bookmaker offers more than L ÷ (L − 1) on the other side, back/back is even better than the lay. Spotting exactly those price differences is what sure-bet software does. The same logic applies when you convert free bets.
With back/back, watch two things. Both bookmakers must settle the market the same way (abandonment, extra time). And in Austria the 5% betting fee can apply to each stake if the bookmaker passes it on, which moves the equivalent odds.
Availability in Austria and Slovakia
As of October 2026, customers in Austria and Slovakia have practically no exchange where they can lay:
- Betfair Exchange is not available to customers in Austria and Germany, according to Betfair's own country FAQ.
- Matchbook restricts customers from Austria and Slovakia.
- In Slovakia, only operators licensed by the gambling regulator ÚRHH may offer online betting. None of the licensed operators runs an exchange, and Betfair and Matchbook are both on the regulator's official list of prohibited offers.
Matched betting in Austria therefore usually runs as back/back between two bookmakers. We do not recommend workarounds via agents or foreign accounts. More background is in our guide to the betting exchange.
Frequently asked questions
What is the liability on a lay bet?
The amount you lose if the result happens: lay stake times lay odds minus 1. On a 50 euro lay at 3.20 that is 110 euros. The exchange reserves it in your account straight away.
Can I lay bets in Austria?
Practically not at the moment. According to its own FAQ, Betfair Exchange is not available to customers in Austria, and Matchbook restricts Austria. The usual alternative is a counter-bet at another bookmaker, known as back/back.
Is back/back as good as laying?
It depends on the prices. Before commission, lay odds L correspond to back odds of L divided by L minus 1 on the other side. If another bookmaker offers at least that price, back/back is as good or better.
Sources
- Betfair: Country closure FAQs
- ÚRHH (Slovakia): Zoznam zakázaných ponúk (list of prohibited offers), as of 19 October 2026
- ÚRHH (Slovakia): licensed online operators, as of 1 January 2026
- Unternehmensserviceportal (USP, Austria): Wettgebührenabrechnung
As of October 2026. Exchanges' country restrictions can change. The 5% commission in the examples is an assumption.
Not betting, legal or tax advice. 18+. Betting involves risk and no profit is guaranteed: odds change, bets get voided and accounts get limited. Only bet money you can afford to lose. Our responsible gambling page lists free help, and the disclaimer applies.