STUDY: How many prep races are ideal fora Kentucky Derby horses?
Kentucky Derby start (Photo by Coady Media/Churchill Downs)
April 22nd, 2025
How many prep races are ideal to prepare a horse for victory in the Kentucky Derby?
In the long-distant past, many different approaches were utilized. Whirlaway (1941) and Citation (1948) ran seven times as three-year-olds before winning the Kentucky Derby. At the other end of the spectrum, Exterminator (1918) and Sir Barton (1919) each won the Derby in their three-year-old debut—no prep races required.
Nowadays, most Kentucky Derby starters enter off two, three, or four prep races. But are all these approaches equally valid? Or is a specific of prep races more likely to yield a peak performance in the Kentucky Derby than other strategies?
Let’s crunch the numbers and find out.
How many prep races are ideal for Kentucky Derby horses: research methodology
To determine how many prep races are ideal, we analyzed the racing schedules of every Kentucky Derby starter since 2000, excluding those from the 2020 Kentucky Derby that took place in September due to COVID-19.
The 24 Kentucky Derbys in our dataset featured 459 starters. We divided these 459 horses into six categories based on the number of races they contested as three-year-olds prior to the Kentucky Derby—the January-through-April window leading up to the first Saturday in May.
Then we analyzed how many Kentucky Derby winners, runners-up, third-place finishers, and top-three finishes each category produced. Finally, we calculated what percentage of starters in each category finished first, second, third, and top-three in the Kentucky Derby, to adjust for the different number of starters in each category.
How many prep races are ideal for Kentucky Derby horses: data analysis
Starts | Wins | Seconds | Thirds | In-the-money | |
| 1 prep | 10 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| 2 preps | 118 | 8 (6.8%) | 8 (6.8%) | 10 (8.5%) | 26 (22.0%) |
| 3 preps | 205 | 11 (5.4%) | 12 (5.9%) | 8 (3.9%) | 31 (15.1%) |
| 4 preps | 105 | 5 (4.8%) | 4 (3.8%) | 4 (3.8%) | 13 (12.4%) |
| 5 preps | 18 | 0 (0.0%) | 0 (0.0%) | 2 (11.1%) | 2 (11.1%) |
| 6 preps | 3 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Since 2000, only 31 horses (6.7% of all starters) entered the Kentucky Derby off one, five, or six prep races at age three. None managed to win the Run for the Roses, and only two (both with five preps) managed to finish in the top three.
It’s far more common to see horses run in two preps (118 horses, 25.7%), three preps (205 horses, 44.7%), or four preps (105 horses, 22.9%). And across these categories, less prep is better prep when it comes to recording top-three finishes in the Kentucky Derby.
Kentucky Derby starters entering off two prep races win at a 6.8% rate, which is 26% better than the 5.4% win rate of horses with three preps and 32% better than the 4.8% win rate of horses with four preps.
Horses with two preps under their belts finish second at a 6.8% rate, 15% better than the 5.9% runner-up rate of horses with three preps and 79% better than the 3.8% runner-up rate of horses with four preps.
Two-prep Derby starters finish third at an 8.5% rate, 118% better than the 3.9% third-place rate of horses with three preps and 124% better than the 3.8% third-place rate of horses with four preps.
Finally, horses with two preps for the Kentucky Derby finish in the top three at a 22.0% rate, 46% better than the 15.1% top-three rate of horses with three preps and 77% better than the 12.4% top-three rate of horses with four preps. It’s also 98% better than the 11.1% top-three rate of horses with five preps.
In short, horses who enter the Kentucky Derby off two prep races outperform horses with three or four preps in every single category.
But that’s not all. Less is still more when comparing horses with three and four preps. The three-prep approach outperforms the four-prep approach in every category.
Horses with three preps win at a 5.4% rate, 13% better than the 4.8% win rate of horses with four preps.
Three-prep horses finish second at a 5.9% rate, 55% better than the 3.8% runner-up rate of four-prep horses.
Horses with three preps finish third at a 3.9% rate, 3% better than the 3.8% third-place rate of horses with four preps.
And lastly, horses exiting three preps finish in the top three at a 15.1% rate, 22% better than the 12.4% top-three rate of horses with four preps. It’s also 36% better than the 11.1% top-three rate of horses with five preps.
Conclusions
“Third start off a layoff” is a popular handicapping angle dating back many years. The theory goes that a horse will be ready for a peak performance in his or her third start following a break from racing.
This angle is alive and well in the Kentucky Derby. Horses who enter the Run for the Roses off only two prep races as three-year-olds have typically taken at least a little time off over the winter, and after running two preps, they have a better chance to deliver a big performance on the first Saturday in May than horses who ran more often leading up to the Derby.
Since 2000, horses entering the Derby off two prep races have been the most likely to perform well. After adjusting for the number of starters representing different prep schedules, horses with two preps are 26% more likely to win than horses with three preps and 32% more likely to win than horses with four preps.
Furthermore, horses with two preps are 46% more likely to finish in the top three than horses with three preps and 77% more likely to finish in the top three than horses with four preps.
The data is compelling: two races is the ideal number of preps for a Kentucky Derby starter to contest between January and April.
