Lay Bet Tool
Lay stake, liability and profit for exchange bets — find the lay that matches your back.
How to Use This Calculator
- Input the back stake amount
- Input the back odds from the bookmaker
- Input the lay odds from the betting exchange
- Input the exchange commission rate (default 5%)
- Read the recommended lay stake, your liability, and profit per 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's a lay bet?
A lay bet is the reverse of a normal (back) bet — you’re betting against an outcome. If the selection loses, you win the backer’s stake minus commission. If it wins, you cover the winnings (your liability).
What's liability?
Liability is the most you can lose on a lay bet. It equals the lay stake times (lay odds - 1). The exchange holds this amount until the event settles.
Which commission rate do I enter?
Betfair’s standard is 5% on net winnings. Smarkets charges 2%. Some exchanges cut rates for high-volume users. Enter the rate tied to your account.
Why are lay odds usually above back odds?
Lay odds sit slightly higher because the exchange has to match backers with layers. That gap (the spread) reflects market efficiency — tighter spreads mean more liquid markets.