Free Online Back/Lay Betting Calculator

Our free online Back/Lay betting calculator calculates the correct Stakes for backing and laying the same selection for the same Net Profit, whether the selection wins or loses. This is commonly known as trading out, greening up or Back/Lay arbitrage.

To help you understood how the Net Profit is obtained, the calculator breaks it down into it Back Bet Profit, Lay Bet Profit and the applicable Commission Paid. The calculator supports both Same Market and Cross-Market bets, enabling you to calculate the level-profit stakes for all possible Back/Lay betting scenarios, including the lucrative ante-post and in-running same-exchange trading.

A popup version is also available for your convenience.

X Back Lay
Total Stake
Same Ex Wins Total Stake Loses
Back Bet Profit -     -    
Lay Bet Profit -     -    
Market Profit -     -    
Commission Paid -     -    
Net Profit -     -    
Yield -     -    

Same-exchange Trading

Like financial traders, you can make immediate profits by betting on the direction of price movements on betting exchanges. All you have to remember is to lay first and back later at the higher price if you expect a price rise. Likewise, if you expect a price to fall or shorten, you'd back first and then lay off later at the lower price.
  1. Select Same-Market.
  2. Enter the Stake and Price of the bet that you've placed.
  3. Enter your target exit Price.
  4. Enter your Commission rate (default value is 5.00%) and press Calculate.
The calculator displays the stake you should use to exit the trade for an immediate level profit.

Same-exchange trading example
The example below assumes that you had originally layed at 1.10 for £150 in anticipation of a price rise. You now want to place an order to back the same selection at 1.20, but don't know what stake to use to ensure the same profit whatever the result.

Example of using the Back/Lay betting calculator to calculate the optimal stakes for trading on a price rise on the same betting exchange

The calculator shows that if you can back it with a stake of £137.50 at 1.20, you'd earn a net profit of £11.87, providing you with a healthy yield of 79.13% on your Total Stake of just £15.
Open popup calculator

Cross-exchange Arbitrage

Whereas trading profits from price movements, arbitrage exploits current price discrepancies. Arbitrage opportunities occur when you can lay a selection in one place site at a lower price than it can be backed elsewhere. If you're placing both bets on different exchanges, Commission will be deducted from their respective profits, making it difficult to calculate the correct level-profit stakes.
  1. Select Cross-Market.
  2. Enter the Price of both the Back and Lay bets.
  3. Enter the value of one stake constraint, caused by available liquidity, a bookmaker's maximum stake limit or just your budget for the arbitrage.
  4. Enter your Commission rates and press Calculate.
If you enter your desired Total Stake as the stake constraint, the calculator will show the correct Back Stake and Lay Stake to ensure a guaranteed level profit, subject to your specified budget.
If you enter the Back Stake or Lay Stake as the stake constraint, the calculator will display the correct level-profit stake for the other bet.

Cross-exchange arbitrage example
Let's assume that a selection that's available to back at 2.50 on Smarkets can also be layed at 2.20 on Betfair. The problem is that there's only £287 available at 2.50 on Smarkets, so you want to know what stake to use on Betfair to ensure a guaranteed level profit, based on the assumption that you'll mop up all the available Smarkets liquidity at 2.50.

Example of using the betting Back/Lay calculator to calculate the optimal stakes for arbing Back and Lay prices between different betting exchanges

The calculator shows you that you should lay £329.72 at 2.20 on Betfair to guarantee a profit of £26.23. Of course, if you're going to be backing the selection with a fixed odds bookmaker, you'd need to change the Commission for the Back Stake to 0.00%.
Open popup calculator

Video Introduction to the Calculator

Which Betting Exchange Should I Use?

If you want to do some Back/Lay betting, you'll need to have an account with at least one betting exchange. There are now 4 major betting exchanges to chose from, so we've compiled brief reviews of each one, including details about their commission rates and links for their free bet offers.


Betfair is the oldest and biggest betting exchange. It also boasts the most markets and the highest liquidity, so is pretty much a must-have account for any serious trader or arber. However, Betfair does suffer occasional system failures, so smart traders and arbers always have a funded account with another betting exchange on standby just in case they need to move quickly to close a trade.

Commission: Sliding rate starting at 5% for UK, Ireland, Italy, Gibraltar and Malta residents, with reductions available depending on the volume of your betting. (Read more)
Free bet: £/€20


Betdaq is a Dublin-based betting exchange established by Irish financier Dermot Desmond (subsequently sold to Ladbrokes). Of the remaining exchange other than Betfair, it probably has the widest range of markets and best liquidity, particularly in the Asian Handicap markets.

Commission: Flat 2% (Different rates for heavy users, such as API users)
Free Bet: £/€10



Designed with the intention to apply financial trading principles to the online betting world, Smarkets is the newest betting exchange. It doesn't yet match Betfair or Betdaq in liquidity or range of markets, but does offer hefty liquidity and tight margins in football markets. It also offers a more sophisticated type of dynamic price/volume graphing than Betfair.

Commission: Flat 2%. (With a Pro Tier for high rollers)
Free Bet: £/€10