The Trigger Bet Calculator is a great tool to help you lock in a profit from offers where you receive a refund if a certain event occurs. 

An example of an offer like this would be money back as a free bet on correct score bets if Luton beat Coventry in 90 minutes. 

For this, we would want to bet on a correct score which would definitely lose if Luton won (so avoid correct scores where Luton win) so on this occasion I have used 0-0.

As you can see we are able to lock in a profit of £2.11 from an offer like this using the Trigger Bet Calculator. We can do this by placing a lay bet on Luton to win, therefore locking in a profit regardless of whether the trigger occurs. 

If our bet on 0-0 wins we would win £66 and win £3.08 on the winning lay of Luton for a total of £69.08. Then we would subtract the lost liability of £66.97 on Smarkets for a net profit of £2.11

If our bet on 0-0 loses but Luton wins we would win £9.05 on the lay bet on 0-0 and make £8 from the free bet for a total of £17.05. Then we would subtract the £10 loss on the 0-0 bet and the £4.93 liability from the lay on Luton for a net profit of £2.12

If our bet on 0-0 loses and Luton do not win we would win £9.05 from the lay bet on 0-0 and £3.08 from the lay bet on Luton for a total of £12.13. Then we would subtract the £10 we lost on backing 0-0 for a net profit of £2.13

You can find a full guide to the Trigger Bet Calculator here