A general guideline is 12×12 feet per stall as a minimum comfortable size. Most horse owners opt for 14×14 feet for larger breeds or added comfort.
Beyond stalls, factor in aisle width (at least 12 feet for easy movement), tack room, wash bay, and hay storage. A modest 4-stall stable typically starts around 40×60 feet. Larger operations need significantly more square footage.
Metal Pro Buildings works with you to size the structure correctly from the start avoiding costly modifications later.