The Arb Calculator is an essential tool for anyone backing and laying on Betfair. It allows you to ‘Green Up’ your bets in seconds. Just enter a few figures and the Arbing Calculator does all the hard work.

The Calculator can work out two types of position, so it’s perfect if you’ve backed and need to lay or vice versa. We also have a Liability Calc which can be used to reduce your position in a bet rather than green up fully.

There is a guide to using this Calc at the bottom of the page, at first it looks complicated but once you start using the Calculator it’s really simple.


No flash installed


Quick Guide To Using The Calculator

  • First enter the commission you pay on Betfair in the ‘Commission Rate’ box (it’s normally 5%).
  • If you’ve already backed a horse or football match then you should to use the first part of the calculator ~ this works out how much you need to lay the bet for. We’ll be using the first part of the calculator because you should always “Back High ~ Lay Low”
  • Most people back a horse or football team first and then want to lay them at lower odds, this guarantees a profit whatever the outcome.
  • So if you’ve backed the Arsenal match to be under 2.5 goals at 1.92 then enter 1.92 in the ‘Enter the Odds You’ve Backed at:’ box
  • Then enter the amount you’ve bet (your stake) in the ‘Enter your Back Stake’ box (example: 5.50) Don’t use £ or $ symbols just numbers (and decimal points if need).
  • Then enter the odds that you want to lay at, for example: 1.63, do this in the ‘Enter the Odds you want to lay at’ box
  • Now click the ‘Calculate Lay Stake’ button, this will tell you the cash amount you need to lay to guarantee a profit. If you’ve followed the example above the calculator will tell you that you need to Lay £6.47 at odds 1.63 to guarantee a profit of £0.92 (Green Up) whatever happens! (Assumes 5% commission entered)
  • If you’ve placed a lay bet first then use the second part of the calculator ~ this tells you how much you need to back for. It’s works in exactly the same way.