How Much Value Do You Need Before Laying a Horse?
How big does the gap between your rated price and the best market price need to be before a lay is worth taking?
Recorded August 2025 for The Grind Ep3: Mastering Betfair SP, Lays & Market Angles – A Professional Approach. Any figures mentioned are from that time.
When I go through the lays, the number I look at first is the probability difference. It is simply the gap between my bullet price, which is my rated price, and the high price in the market, expressed as a percentage. Not the gap between two different bookmakers, and not the gap between my price and some random board. The gap between my rating and the best price available. That number tells me whether a horse is genuinely under the odds or whether it only looks like a lay on paper.
How the number is worked out
Take Royal Edition. My bullet price is $2.10. The high price is $1.70. Turn both into percentages. The $2.10 is about 47 per cent. The $1.70 is about 62 per cent. The difference between those two is about 17 per cent. That is the probability difference. It runs the same way down the whole list. If I have one at 15s and the top price is 15s, the difference is zero. If I have one at $2 and the market is $4, that is a small number the other way. If I have one at 12s and the market is about 16s, that is four. The important part is that I am always comparing the high price to my bullet price, nothing else.
Small margins and drifters give you nothing
The interesting part is what happens when you break the lays up by that number. Start with the ones where the difference is negative. These are official lays where the horse has actually drifted into overs. I might have had one at $4, it was $2.80, and by the time you get to it the price is $4.40. Heavy drifters. There are 169 of them with 11 winners, and you are not making anything laying them. That is the point where you drop off laying a horse.
Then take the small underlays, the ones sitting between zero and five per cent. The top price average across this is around 105 per cent, so it is a solid market, not one or two silly boards being cherry picked. Combine the drifters and the small margins together and back the lot instead, and you are in front. If backing them works, laying them clearly does not.
The results sit above five per cent
Now go the other way and look at everything with a probability difference from 5.1 up. There are 566 of them. Laying those at Betfair SP, before commission, returns 16 per cent. That is where the whole result lives. Royal Edition at $1.70 against a rating of $2.10 is a good margin. That is the type you want.
So before you lay anything, work out the gap between your rated price and the best price on offer. If it is under five per cent, or the horse has drifted into overs, leave it alone.
Every race on the card, rated, with Kingsley's selections and the speed maps behind them. Your first day is free, no card needed.
More from Kingsley
- "Why Does a Horse Only Win Off a Slow Early Tempo?"
- How Much Should Track Condition Change Your Prices?
- How a Professional Punter Breaks Down the Japan Cup
From the full video: The Grind Ep3: Mastering Betfair SP, Lays & Market Angles – A Professional Approach
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