If you are attempting to figure the carrying capacity of land for a horse, then a good rule of thumb is 1-1/2 to 2 acres of open, intensely managed land per horse. In Kentucky on properly managed pasture, 2 acres will support the forage needs of a horse, and 2 to 3 acres will support a mare and foal up until weaning time. But this is highly variable depending on location. Little research has been done on the space requirements of horses.
One acre is 43,560 square feet, or approximately 210 feet x 210 feet. Obviously, many people keep horses on smaller plots of land and do not depend on the land to provide any forage.
The minimum area needed to house a horse for turnout is 0.1 (one-tenth) of an acre, approximately 4,500 square feet, or 75 feet x 60 feet for an exercise lot.
