Horses in Photo Finish Live are graded based on their genetics.

The Grades are:

D is the lowest grade and SSS is the highest.  Each grade is subdivided. A horse with a (+) is stronger than a horse with no marker or one with a (–).

A horse's attributes (Start, Speed, Stamina, Finish, Heart, and Temper) are all graded as well. Each of these grades shows the strength of the horse in that specific trait. A horse's Grade is the average of it's attribute grades.

Grades are a range. An S grade is not a single number but a small range of numbers. Two horses with S grade Start will have very similar Start but probably won't have the exact same value.