Making an exchange lay bet is not as simple as calculating your potential profit in a normal back bet. With a back bet you simply multiply your stake with the odds, subtract your stake and hey presto the figure left is your potential profit.
The lay bet calculation is a little bit more involved and has nothing to do with the picture above (That is just the Kelly Criteria equation for anyone who wants to look it up)
To calculate your liability (How much you would lose if the bet “won” remember with a lay bet you are betting your selection will lose) the following equation is used
Liability = (Backers stake x (Lay odds – 1)
For instance in the 15:05 at Ascot yesterday (1st Oct 2021) Chalk Stream was 3.6 to lay. You don’t think as others do and think it has no chance and want to win a tenner if it loses so you need to know how much you would lose if it wins
Liability = (£10.00 x (3.6 – 1) = 10 x 2.6 = £26.00
To win your £10.00 you stand to lose £26.00 if Chalk Stream wins.
This is the basic calculation and you would need to take off your commission from any winnings.
For instance if your Betfair commission rate is 5% then your £10.00 profit would be subject to a 5% reduction equalling 50p leaving you with a total profit of £9.50 if Chalk Stream loses and a £26.00 loss if it wins.
To make this lay bet you would need at least £26.00 in your betfair account. Things get really interesting when you need to calculate your liability when making Back to lay bets.
Lets take todays first Back to Lay selection on the In-Running Trading Tool feature.
Highfield Princess is running in the 13:30 at Ascot total (2nd Oct 2021) and is currently at 4.3 to win so we back her at that price for £10.00 – a simple no-nonsense back bet, we lose a tenner if it loses and win £33.00 if it wins.
I personally lay my “back to lay” selections at a set 15 tick “drop” from whatever price I backed. For this I use my own “Betfair tick counter” in the form of an excel spreadsheet which I made myself and is available free to download at the end of this page.
A 15 tick drop from 4.3 is 3.4 so now I need to calculate an equal profit liability lay order at odds of 3.4 so that if the horse trades in-play at odds of 3.4 I will win whatever the outcome.
To do this I simply use one of the many “Matched Bet” Calculators on the web, my favourite being Odds monkeys free bet calculator as shown below
As you can see from the screen shot above if the odds in-play reach our 15 tick drop we would win at least £1.72 even if the horse loses.
As promised above my betfair tick counter is available for free download by clicking the link below
The example shown on this page wasn’t plucked out of thin air. I subscibe to a website called In-Running Trading Tool which provides daily data on various trading strategies ranging from Back to Lay trading to “DOBBING” or Double or Bust trading on every horse running that day. Highland Princess is just one of several selections highlighted by the site for todays racing. I am currently on a 5 bet winning streak and playing with free money after taking my original stake out after the 3rd bet. These trades were as follows
28th Sept – 13:35 Ayr – Le Cheval Rapide – Trade won Horse lost
29th Sept – 13:40 Bangor-on-Dee – Robin Des Theatre – Trade won Horse lost
30th Sept – 14:00 Warwick – Friend or Foe – Trade won Horse lost
01st Oct – 13:35 Fontwell – Pasvolsky – Trade won Horse lost
01st Oct – 14:45 Fontwell – Keepyourdreamsbig – Trade won Horse lost
A full breakdown of these backed and liad bets can be seen from my downloaded excel file below
I used the minimum stake of £2.00 for the initial bet adding my profit to this each time until I had won enough to bet with just profits.
To get a free trial of the In-Running Trading Tool please click the link below
Please visit my blog to read about these and other trading posts
Betornot 