With this technique we are looking at looking at offers such as Bet365's 'Back a winner over 5.0 and get a risk free bet' or Betfair Sportsbooks 'Back a winner over 4.0 and get a free bet'.
As we only get a free bet if the horse wins, we don't want to lose any money if our horse loses, but if it wins, we do not mind losing a little bit more than our qualifying loss as we are getting a free bet. This technique is overlaying.
As an example Flaming Spear was available to BACK at Bet365 at Odds of 7.0 and available to LAY at odds of 7.2 at Smarkets. If we put them calculations into the calculator (and click mode: advanced) we come up with the following:
Here we can see that a normal match would give us a loss of £2.25.
If we look at overlaying, we can see that if the horse wins we will lose £16.32 and if the horse loses we will lose nothing. If the horse does win, we will get a £50 risk free bet for the next race. Assuming we can get a 80% return from that risk free bet, we will make £40 guaranteed profit. So if the horse loses we have no loss and if it wins we can expect the following return:
Horse wins = -£16.32
Risk free bet = +£40
Total profit = +£23.68
Remember we must still find a good match at our risk free bet profit must cover our overlay losses.