Lay Bet Calculator

A lay bet is the inverse of a back bet. When you lay a selection, you act as the bookmaker for that bet: you accept someone else's money in return for paying out if their selection wins. You collect the stake when the selection loses, and pay out the liability when it wins. Lay betting is only available on betting exchanges (Betfair, Smarkets, Betdaq), not at high-street bookies, because exchanges match individual backers and layers against each other.

The calculator takes the lay odds, the lay stake (the amount you'd collect if the selection loses), and the exchange commission percentage, and shows you three things: your liability (how much you must pay out if the selection wins), the required balance you need in your account before placing the bet, and your profit and loss in each scenario. Liability is always (lay odds - 1) × lay stake.

Lay liability is what makes lay betting feel different from back betting. If you lay a selection at odds of 5.0 with a £20 stake, your liability is £20 × (5.0 - 1) = £80. You need at least £80 free in your exchange account to place that lay bet, even though you only collect £20 (less commission) if you win. This is why exchange accounts often hold larger balances than back-only bookmaker accounts: the working capital required scales with the odds you're laying.

The higher the lay odds, the bigger the liability for the same potential profit. Laying at 2.0 with a £20 stake means £20 liability (£20 risked to win £20). Laying at 10.0 with a £20 stake means £180 liability (£180 risked to win £20). Laying short prices is therefore more capital-efficient than laying long shots, which is one reason many lay-bettors focus on favourites. For the back side of arbitrage, the [Dutching Calculator](/dutching-calculator) shows how to spread stakes across multiple selections instead.

Three main uses. Matched betting: combine a free bet at a bookmaker with a lay at the exchange to lock in most of the free bet's value as cash. Trading: lay at one price expecting it to drift, then back at higher odds to lock in a profit regardless of outcome. Hedging: if you've already backed a selection, laying it back at lower odds can lock in a guaranteed profit before the event happens.

Commission on exchanges typically runs 5% on Betfair (lower for high-volume customers, the famous 'premium charge' aside), 2% on Smarkets and Betdaq. Commission applies only to your net winnings on a market, so if you lose more than you win in a market the commission is zero. The calculator's commission setting affects only the profit-if-loses scenario, since the loss-if-wins scenario already accounts for the full liability.