Mare Gestation Calculator

Are you wondering when your pregnant mare will foal? Use our Mare Gestation Calculator to find out! The average gestation length in the mare ranges from 320 to 362 days; most mares will foal within 330-345 days of successful breeding. However, mares have successfully foaled with gestation lengths outside this range.

Please Note: The Mare Gestation Calculator is intended for use only as a foaling date estimation tool for horses. It does not consider differences between individual mares. is not responsible for problems or injuries arising from the use/misuse of this tool or for any inaccuracy in the foaling date estimate of an individual horse.

What date was the mare bred?


Estimated foaling date:

Select a breeding date in the calendar to see the estimated foaling date range.


  • This calculator gives a gestation range of 331-346 days from breeding (adding a day for ovulation to a 330- to 345-day range).
  • Individual mares tend to have their own gestation length tendencies.
  • Ponies, on average, tend to have shorter gestation periods than full-size horses.
  • This calculator is not intended for gestation estimation in donkeys or other equids—only horses.


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