Betting calculator
Back/Lay Calculator
Use this calculator to work out the lay stake needed to balance a back bet and lay bet, including lay liability and exchange commission.
Choose your back/lay calculation
Use standard mode for normal back bets, or free bet mode for stake-not-returned free bet examples.
A lay stake of £151.52 would balance the result at about £48.48 profit whether the selection wins or loses.
What is a back/lay bet?
A back/lay calculation compares a normal back bet with a lay bet on the same selection. Backing means betting that the selection will win. Laying means betting that the selection will not win.
Back/lay calculations are commonly used in exchange betting, matched betting, hedging and trading because they show how much to lay, how much liability is created, and what the result would be if the selection wins or loses.
What this calculator shows
- The lay stake needed to balance the back and lay position.
- The lay liability on the exchange.
- The result if the selection wins.
- The result if the selection loses.
- The difference between the two outcomes.
Standard back bet formula
In standard mode, the calculator assumes you have placed a normal back bet where your stake is returned if the bet wins.
Lay stake = back stake × back odds ÷ (lay odds − commission)
Lay liability = lay stake × (lay odds − 1)
If selection wins = back profit − lay liability
If selection loses = lay stake after commission − back stake
Standard back/lay example
Suppose you back a selection with £100 at decimal odds of 3.00, then lay the same selection at odds of 2.00 with 2% exchange commission.
| Input | Value |
|---|---|
| Back stake | £100.00 |
| Back odds | 3.00 |
| Lay odds | 2.00 |
| Commission | 2% |
| Lay stake | £151.52 |
This balances the result at about £48.48 profit whether the selection wins or loses.
Free bet stake-not-returned mode
Some free bets are stake not returned. This means that if the free bet wins, only the profit part is paid. The free bet stake itself is not returned.
Free bet mode adjusts the lay stake formula to reflect this.
Lay stake = free bet stake × (back odds − 1) ÷ (lay odds − commission)
If selection wins = free bet profit − lay liability
If selection loses = lay stake after commission
Back bet vs lay bet
| Bet type | What you want to happen | Main risk |
|---|---|---|
| Back bet | You want the selection to win. | You lose your back stake if it loses. |
| Lay bet | You want the selection not to win. | You pay the lay liability if it wins. |
When used together, a back bet and lay bet can be used to reduce risk, hedge a position or balance outcomes. The key is calculating the lay stake and liability correctly.
Back/lay vs hedging
Back/lay betting and hedging are closely linked. Hedging is the broader idea of placing another bet to reduce risk or balance a position. Back/lay is one of the most common ways to do that on a betting exchange.
If you want to calculate a position where you may have laid first and backed later, use the Hedge Bet Calculator. It includes both back-first and lay-first modes.
Common back/lay mistakes
Forgetting commission
Exchange commission affects the correct lay stake and final profit. A calculation that ignores commission may look better than the real result.
Confusing lay stake and liability
The lay stake is not the amount you risk. Your liability is the amount you can lose if the selection wins.
Using the wrong free bet type
A stake-not-returned free bet needs a different calculation from a normal cash bet. If you use the wrong mode, the lay stake may be wrong.
Not checking liquidity
Exchange odds may be visible, but there may not be enough money available to match your full lay stake at that price.
Relying on odds that have moved
Back/lay calculations depend on the exact odds used. If the lay odds change before the bet is matched, the result can change.
Related betting calculators
Back/lay calculator FAQs
What does a back/lay calculator do?
A back/lay calculator works out the lay stake needed to balance a back bet and lay bet, including exchange commission and lay liability.
What is lay liability?
Lay liability is the amount you risk on the exchange if the selection you lay goes on to win.
Why does commission matter?
Commission reduces your exchange winnings. This changes the correct lay stake and final result.
What does stake not returned mean?
Stake not returned means the free bet stake is not included in the payout. Only the profit part is paid if the free bet wins.
Is this the same as a hedge calculator?
It is related. This calculator focuses on backing first and laying the same selection. The Hedge Bet Calculator also covers lay-first, back-later positions.