The Kentucky Derby allows a maximum of 20 horses to run each year. For the 2025 Kentucky Derby, the field was set to have 20 horses, but after a couple of scratches, 19 horses competed in the race

. In general:

• The starting gate has 20 post positions.
• Up to 20 horses can enter and run.
• If horses are scratched (withdrawn), fewer than 20 may run.

So, typically, 20 horses run in the Kentucky Derby, but the actual number can be slightly less due to last-minute scratches