Laying means betting that something won’t happen. You’re the bookie. The lay calculator above shows how much you could lose, which on an exchange is called the liability, because that number surprises people.
Lay a horse for £10 at 4.0. If it loses, you keep the £10, minus 2% commission, so £9.80. If it wins, you pay the backer £30. Lay the same £10 at 11.0 and the liability is £100. Same £9.80 if it loses, ten times the risk if it doesn’t.
Lay calculator: stake or liability
Exchanges let you enter the lay either way, so the calculator does too:
- Lay stake (backer’s stake): what you win if the selection loses, before commission.
- Liability: the most you’re prepared to lose. Put £50 in at 6.0 and the calculator tells you that’s a £10 lay.
Add the exchange’s commission and you’ll see the profit after the cut, the loss if it wins, and the implied chance the exchange is pricing in.
When people lay
Mostly three reasons. Matched betting, where you lay off a bookie bet (use the matched betting calculator for that, it handles both sides). Trading, backing early and laying later at shorter odds. And opinion: you think the favourite is overrated and you’d rather take the bet than back the field.
Laying favourites wins most of the time. That’s the trap. A short-priced lay wins often and loses big, and a single bad result can wipe out weeks of small wins. Know your liability before you click, every time.
The formulas
Liability = lay stake × (lay odds − 1) Lay stake from liability = liability ÷ (lay odds − 1) Profit if it loses = lay stake × (1 − commission)
Commission only comes off when you win, and only on the net winnings in that market.
Liability is real money. Never lay more than you could pay out. BeGambleAware.org is free and confidential if it stops being fun.