Two horses come back from the same race in the same time. One carried eight stone ten, the other ten stone two. Same clock, very different effort. The horse that looks slower on paper may well be the better one. That gap, between what a stopwatch sees and what a horse is doing under its weight, is what a weight-adjusted speed rating is built to show.
Race Advisor’s version is called SPDFIGLrAdj. The name is a mouthful, but the logic is clean: take a horse’s speed figure from its last race, then adjust it for the weight it carries today. Heavier than last time and the figure comes down. Lighter and it goes up. The question here is whether that adjusted figure helps find winners, or whether the market has already done the sums.
Does a weight-adjusted speed rating beat the market? On its own, it is a good guide rather than a shortcut. In an earlier Race Advisor analysis of 1,177,186 UK runners from July 2013 to March 2026, rank 1 on SPDFIGLrAdj had an A/E of 1.06 at Betfair SP (the exchange’s closing price) after 2% commission. A/E is actual winners divided by the winners the odds implied, so 1.06 is a little better than the market expected. The strongest results came from jumps racing on softer ground, where stacked conditions pushed the A/E above 1.20.
What does a weight-adjusted speed rating measure?
A raw speed figure says how fast a horse ran last time. It does not say whether today’s weight helps or hinders. A horse that won easily off nine stone and now carries eleven is running a different race, even though the figure on the card looks the same.
SPDFIGLrAdj does the sum for you. A value of zero means the horse is, on paper, weighted the same as its previous effort. A positive value means it carries less weight today than it did when it ran that figure, which is the upside case. A negative value means it carries more. The rating is then ranked within each race, so the highest adjusted figure becomes rank 1.
You can read it three ways. The rank shows where the horse sits against its rivals today. The raw figure shows how strong the weight signal is. The gap to the top-rated horse shows how clearly the rating separates the field.
How does the rank perform across 1.17 million runners?
The rank gives a clean strike-rate gradient. Rank 1 won 19.6% of the time across 159,580 runners. Rank 2 won 16.2% across 157,462 runners. Rank 3 won 14.0%, rank 4 won 12.2%, and everything from rank 5 down won 8.3% across 564,176 runners. Five steady steps downward is exactly what a sensible rating should produce.
Rank 1 had an A/E of 1.06, with a return of +7.5% per unit staked after commission, over nearly 160,000 bets. Rank 1 won about one race in five, so that figure includes every losing bet too. It is a modest, historical result, and it shows the prices understated these runners’ win rate over that period. For context, the Race Advisor database check across Great Britain and Ireland from 1 July 2013 to 14 October 2026 puts the favourite at 34.4% of 167,257 races, with an A/E of 1.00. The favourite wins more often than SPDFIGLrAdj rank 1, but they are not always the same horse, and the difference between them is where the interesting angles sit.
What does the raw rating add?
Rank tells you who is on top. The raw rating tells you how strong that top signal is.
Splitting every runner by raw SPDFIGLrAdj value gave a clearer picture than rank alone. Horses rated 75 or higher, the strong “carrying less today than last time” signal, won 16.5% of the time across 131,660 runners, with an A/E of 1.12 and a return of +15.1%. Horses between 0 and 75 had an A/E of 1.07 across 319,742 runners. Ratings from -30 to 0 sat at 1.01, and below -30 the A/E was 1.01 too, so the benefit is concentrated in the positive ratings.
Reading both together is the practical point. A rank 1 horse with a raw rating of -20 is still the best in its race, but the signal is gentle. A rank 3 horse with a raw rating of 90 may be sitting behind stronger rivals today, and the weight-adjusted speed underneath is still strong.
Where does the edge show up most?
The headline A/E of 1.06 is an average across all UK racing. Splitting rank 1 by race type is far more useful.
Chase Turf is where the rating shone. Rank 1 won 23.4% of turf chases across 22,487 runners at an A/E of 1.23, with a return of +33.9%. Hurdle Turf followed at an A/E of 1.09 across 36,200 runners and +15.2%. National Hunt racing is where the weight adjustment adds the most.
Flat racing is the closest-priced. Rank 1 on Flat Turf had an A/E of 1.01 across 58,140 runners, and Flat All-Weather was 1.00 across 36,592 runners. The Flat market reads the weight column quickly, so on the Flat it is best to treat the rating as one voice among several.
Going tells a similar story. On Heavy ground rank 1 had an A/E of 1.17 across 9,782 runners, with a return of +23.1%. Yielding was 1.12, Soft 1.11 and Good To Soft 1.07. On Good To Firm and Standard all-weather the figure sat close to 1.00. Going is the ground description, and the softer it is, the more weight tends to matter and the more the rating adds.
Stack the conditions and it sharpens. Rank 1 in a jumps turf race (Chase or Hurdle) on Heavy, Soft or Good To Soft going won 23.7% of the time across 11,833 runners at an A/E of 1.25, with a return of +42.0%. That is the strongest segment in this analysis, found by splitting the data, so treat it as a strong lead rather than a settled rule. It is a large sample of almost 12,000 settled bets. It is a record of past results, not a promise of future ones.
How do you use it well?
The most useful split is between agreeing with the market and disagreeing with it. When SPDFIGLrAdj rank 1 was also the Betfair SP favourite, it won 38.2% across 45,118 runners, at an A/E of 1.05, because the price already reflects the view. When rank 1 was not the favourite, it won 12.2% across 114,462 runners, but the A/E held at 1.07 with a return of +7.8%. The value is concentrated where the rating and the market see the race differently.
So treat the rank as a shortlist tool and follow a short routine:
- Read the raw rating beside the rank. A raw 75 or more is a stronger signal than a rank 1 with a low figure.
- Prefer jumps and softer ground. That is where the numbers were strongest.
- Look at Classes 2 to 5. The effect was strongest there, and Class 6 was close to the market.
- Check the A/E for the mix you have in mind. Pick the race type, going and class together and see how that group has performed. Our guide to A/E ratios shows how.
What is the takeaway?
A weight-adjusted speed rating does something real. It carries a measurable edge across more than a million UK runners, a touch ahead of the market, with a tidy strike-rate gradient from rank 1 to rank 5. Used as one input, it is a very good way to shortlist.
Its best form is the focused one: the top rank, on softer ground, in a jumps race, with a positive raw rating. That is where the A/E went above 1.20 on nearly 12,000 bets. Our single-rating profit test shows the same pattern for the form ratings: one figure is the starting point, and the conditions are the rest of the answer.
To see how the weight-adjusted speed ratings rank this afternoon’s runners, open today’s race cards and look for races that match the conditions above: a jumps race, softer going and a high raw rating.
