Back/Lay betting calculator

The Back/Lay calculator calculates the stakes for:

• Locking in a guaranteed level profit after a price rise (lay first, back later)
• Locking in a guaranteed level profit after a price fall (back first, lay later)
• Arbing Back and Lay prices for a guaranteed level profit (back and lay at same time)

Locking in a guaranteed level profit after a price rise (lay first, back later)
In this example, you layed Tim Henman at 1.10 for £1,000 when he was 2 sets up because you thought he would crack and let Tursonov back into the match. Sure enough Tursonov won the next set, pushing Tiger Tim's price out to 1.50. You would like to close the trade and go all green. Arb Cruncher instructs you to back Henman for £733.33 in order to win £253.34 whatever the final result. Other terms for a price rise are "lengthening" and "drifting".



Locking in a guaranteed level profit after a price fall (back first, lay later)
You backed Chelsea 2.25 before the teams were announced and they have now shortened to 2.00 on news of their opponents' depleted line-up. Wary of the draw, you want to green up for a guaranteed profit before the match has even started. Arb Cruncher instructs you to lay the Blues for £562.50 for a level profit of £59.37, ie the P&L of all 3 outcomes on Betfair would be a green £59.37. Other terms for a price fall are "shortening" or "coming in".


Arbing Back and Lay prices for a guaranteed level profit (back and lay at same time)
A horse can be simultaneously backed on Betdaq at 2.54 and layed on Betfair at 2.24. There is only £500 available on Betdaq, so you would like to know how much to lay the horse for on Betfair to guarantee a level profit after commission. Arb Cruncher instructs you to lay £569.36 on Betfair to guarantee a profit of £40.89 whatever the result.