Mare Gestation Calculator
Calculate a mare foaling date and due window
Enter a breeding, cover, or ovulation date to estimate a mare's foaling date, likely foaling window, 300-day watch date, and barn prep schedule.
Choose a breeding date to see the foaling calendar.
How to use this horse foaling date calculator
Use the date the mare was bred, covered, artificially inseminated, or ovulated. The calculator adds the selected gestation length and gives you an estimated foaling date plus an early-to-late window.
For general planning, 340 days is a common mare gestation estimate. Actual foaling can happen earlier or later, so use the window and watch dates to plan checks, supplies, and barn readiness.
Quick foaling preparation checklist
- Mark day 300 and the early edge of the foaling window on your barn calendar.
- Prepare a clean, safe foaling stall before the first likely date, not the middle due date.
- Check foaling kit supplies: clean towels, tail wrap, iodine or navel dip, flashlight, thermometer, watch notes, and emergency phone numbers.
- Record the actual foaling date so future custom gestation settings match your mare's history.
Mare gestation FAQ
What is the average horse gestation length?
Many horse foaling charts use about 340 days from breeding to foaling. Normal mares may foal several weeks earlier or later, so this calculator shows a planning range around the estimated date.
What date will a mare foal if bred today?
With the standard 340-day setting, the estimated foaling date is 340 days after today's breeding date. Use the date input above to calculate the exact calendar date and watch window.
Should I use breeding date or ovulation date?
If you know the ovulation date, it can be a better starting point. If you only know the cover or breeding date, use that date and keep the wider foaling window in mind.
Is this a veterinary tool?
No. It is a planning calculator for barn calendars. For pregnancy concerns, early labor signs, retained placenta risk, nutrition, or health questions, work with your veterinarian or experienced equine professional.