Mare Gestation Calculator - Horse Gestation
Calculate horse foaling due date and monitor mare pregnancy with 338-day gestation timeline
Calculate Mare Foaling Date
Enter successful breeding date
Leave blank to use today's date
Select your horse's size category
Example Calculation
Typical Mare Gestation Example
Horse type: Average Quarter Horse Mare
Mating date: April 15, 2025
Gestation period: 338 days (11+ months)
Expected foaling date: March 19, 2026
Foaling window: March 12-27, 2026
Expected offspring: 1 foal (twins extremely rare)
Calculation
Foaling Date = Mating Date + 338 days
Foaling Date = April 15 + 338 days
Foaling Date = March 19, 2026
Normal Range: 331-346 days
Earliest Foaling: March 12, 2026 (331 days)
Latest Foaling: March 27, 2026 (346 days)
Signs of Approaching Foaling
Udder Development
2-6 weeks before
Udder enlarges and fills with milk
Waxing
1-4 days before
Waxy plugs form on teats
Behavioral Changes
Hours before
Restlessness, sweating, pacing
Foaling Preparation
Prepare clean, safe foaling stall
Monitor mare closely after day 320
Have veterinarian's contact information ready
Maintain proper nutrition during late gestation
Ensure vaccinations are up to date
Horse Breeding Facts
Breeding Season
Natural season: April to September
Foaling Duration
Stage 1: 2-4 hours, Stage 2: 15-30 minutes
Typical Outcome
Single foal, twins extremely rare (1 in 10,000)
Understanding Mare Gestation & Horse Pregnancy
Horse Gestation Period
The average horse gestation period is 338 days (about 11 months), but this can vary based on the mare's size and breed. Ponies tend to have slightly shorter pregnancies (~335 days), while draft horses may carry foals longer (~342 days).
What is Foaling?
- •Foaling is the process of a mare giving birth to a foal
- •Most mares foal during nighttime hours
- •The process typically takes 2-4 hours total
- •Twins are extremely rare in horses (1 in 10,000 births)
Calculation Formula
Foaling Date = Mating Date + Gestation Days
- Ponies: 335 days average
- Average Horses: 338 days average
- Draft Horses: 342 days average
- Normal Range: 331-346 days
Pregnancy Monitoring
Regular veterinary checkups, proper nutrition, and monitoring for foaling signs are essential for a successful pregnancy and healthy foal delivery.
Breeding Tip: Natural breeding season occurs from spring through summer (April-September) when daylight hours are longer.