Calculate a Lay Bet
Exchange lay stake, liability and profit matched to a back bet.
How to Use This Calculator
- Enter the back stake amount
- Drop in the back odds from the bookmaker
- Drop in the lay odds from the betting exchange
- Set the exchange commission rate (default 5%)
- Instantly see the recommended lay stake, your liability, and profit for every 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 flips a standard (back) bet on its head. When you lay, you’re betting against something happening. If the selection loses, you bank the backer’s stake minus commission. If it wins, you cover the winnings — that’s your liability.
What does liability mean in lay betting?
Liability is the most you can lose on a lay bet. It works out to the lay stake times (lay odds - 1). The exchange holds that amount until the event settles.
Which exchange commission should I enter?
Betfair runs 5% standard commission on net winnings. Smarkets runs 2%. Some exchanges cut rates for high-volume users. Plug in whatever rate applies to your exchange account.
Why do lay odds usually sit above back odds?
Lay odds run a touch higher because the exchange has to match backers with layers. That gap (the spread) between back and lay odds reflects how efficient the market is. Tighter spreads signal more liquid markets.