Toolkit
To make your life easier here are some tools.
Bet Matcher
A spreadsheet to take all the hard work out of calculating bets. Enter all the details for either Qualifying or Free Bets and it will tell you how much you need to lay at the betting exchange to ensure the same guaranteed profit irrespective of the result.
Multiple Odds Matcher
Sometimes it is not possible to lay the whole of your back bet amount at a single price. This spreadsheet calculates the amount you need to lay at the new price should this occur.