Lay Bet Helper
Find the lay stake, liability and profit to match a back bet on an exchange.
How to Use This Calculator
- Enter the amount of your back stake
- Add the back odds from the bookmaker
- Add the lay odds from the betting exchange
- Enter the exchange commission rate (5% is the default)
- See the suggested lay stake, your liability, and the profit for each possible outcome
Formula
Lay Stake = (Back Stake × Back Odds) / (Lay Odds - Commission Rate)
Liability = Lay Stake × (Lay Odds - 1)
Profit if Back Wins = Back Stake × (Back Odds - 1) - Liability
Profit if Lay Wins = Lay Stake × (1 - Commission Rate) - Back Stake
Frequently Asked Questions
What is a lay bet?
A lay bet is the flip side of a regular (back) bet. When you lay something, you’re betting that it won’t happen. If the selection loses, you collect the backer’s stake minus commission. If it wins, you have to cover the winnings (that’s your liability).
What does liability mean in lay betting?
Liability is the most you could possibly lose on a lay bet. You work it out by multiplying the lay stake by (lay odds - 1). The exchange holds on to this amount until the event has been settled.
Which exchange commission should I enter?
Betfair takes 5% as its standard commission on net winnings, while Smarkets charges 2%. Some exchanges give reduced rates to high-volume users, so just enter the rate that matches your particular exchange account.
Why are lay odds usually a bit higher than back odds?
Lay odds sit slightly higher because the exchange has to pair backers up with layers. The gap (the spread) between back and lay odds reflects how efficient the market is. Tighter spreads point to more liquid markets.