Lay Bet Calc
Lay stake, liability and profit to match any back bet.
How to Use This Calculator
- Enter the back stake amount
- Enter the back odds from the bookmaker
- Enter the lay odds from the betting exchange
- Enter the exchange commission rate (default 5%)
- 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 normal (back) bet on its head. When you lay, you’re betting against something happening. If the selection loses, you scoop 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. The math is simple: lay stake times (lay odds - 1). The exchange ring-fences that amount until the event settles.
Which commission rate should I plug in?
Betfair takes 5% standard commission on net winnings. Smarkets takes 2%. Some exchanges trim the rate for heavy hitters. Enter whatever applies to your own exchange account.
Why do lay odds tend to top back odds?
Lay odds sit a touch higher because the exchange has to pair backers with layers. That gap (the spread) between back and lay odds reflects how efficient the market is — tighter spreads signal more liquid markets.