Q: What is the gestation period for a mare?
A: The average gestation length in mares ranges from 320 to 362 days. Most mares foal down within 330-345 days of successful breeding. Having said this, many mares will successfully foal down with gestation lengths outside of this range.
It is also worth noting that ponies, on average, tend to have shorter gestation periods than horses, and that individual mares do tend to have their own gestation length tendencies.