The Farmshare Mare Gestation Calculator can be used to quickly estimate a foal’s due date based on the average mare gestation period. On average, horses are pregnant for 320 to 362 days, with 340 days being the standard used for foaling date calculations.

Simply enter the breeding date to estimate the foaling date. Foaling date = breeding date + 340 days

Horse Gestation Length

The average gestational length of horse is 11 months or approximately 340 days. Although the gestational period of horses can range between 320 to 362 days depending on the mare, season, and individual circumstances.

• Average horse gestation length: 340 days
• Short horse gestation length: 320-325 days
• Long horse gestation length: 360-370+ days

Factors That Influence a Horse’s Gestation Length

Although the average horse gestational length is 340 days, your horses gestational length can vary based on a number of factors including:

• Foal Sex: Colts (male foals) are often carried a few days longer than fillies (female foals).
• Breed differences: Some horse breeds naturally have slightly shorter or longer gestation lengths.
• Individual variation: Just like people, every mare is different.