Though a horse's height is traditionally measured at the withers, the common height measurement on cattle is at the hip; and, instead of being measured in hands, they are measured in Frame Scores.  A mature frame score is calculated with the three year height, and even if the animal grows in later years it will still be considered the same frame score.  It is not often that an animal will grow any more than an inch after their third year of age, but on occasion one can grow as much as two more inches.  In fact, with Herefords there is more variation between spring or autumn measurements, since they gain weight on the good feed of summer and lose it during the winter.     
Here at Point of Rocks Ranch, we use a three-year height to calculate the mature frame score.  Any frame score calculated with an earlier measurement is designated with an EST (estimated). Generally, frame scores are not calculated with anything younger than a yearling measurement since it is usually more accurate to use the average of the sire and dam frame scores than the height of the calf.  The height of a calf before one year of age depends more on the dam's milk production than breeding. 
Initially, a frame score chart may look a little confusing, but with practice it is a very handy tool.  Simply find the age of the animal in months (or a mature age of two or three years) in the column labeled Age (in Months).  Then, by looking across to the animal’s height in inches, you will find the frame score category in which the animal belongs.  Please note there is a chart for cows and another for bulls; be sure to use the correct chart!
The charts provided below are for Miniatures (Frame Scores 0-0000) and Classics (Frame Scores 1-3).  Modern Herefords today are much larger, usually Frame Scores 4-10.