How long is a horse pregnant?
Mares average about 340 days (11 months), but anything from about 320 to 370 days is considered normal. Mares bred early in the year often carry longer than mares bred in summer, and individual mares tend to repeat their own pattern.
Foaling date = breeding date + 340 days
Pregnancy milestones
| Day | What happens |
|---|---|
| 14 to 16 | Ultrasound to confirm pregnancy and rule out twins |
| 25 to 30 | Heartbeat visible on ultrasound |
| Months 5, 7 and 9 | Equine herpesvirus (EHV-1) vaccines, per your vet |
| About 300 | Pre-foaling boosters |
| 320 to 370 | Normal foaling window |
Sample foaling dates
| Bred | Foaling (day 340) | Earliest (day 320) | Latest (day 370) |
|---|---|---|---|
| Jan 15, 2026 | Dec 21, 2026 | Dec 1, 2026 | Jan 20, 2027 |
| Mar 15, 2026 | Feb 18, 2027 | Jan 29, 2027 | Mar 20, 2027 |
| May 15, 2026 | Apr 20, 2027 | Mar 31, 2027 | May 20, 2027 |
| Jul 15, 2026 | Jun 20, 2027 | May 31, 2027 | Jul 20, 2027 |
| Sep 15, 2026 | Aug 21, 2027 | Aug 1, 2027 | Sep 20, 2027 |
| Nov 15, 2026 | Oct 21, 2027 | Oct 1, 2027 | Nov 20, 2027 |
See the foaling season guide for signs, labor stages and when to call a vet, and the horse gestation chart for a date for every breeding day.
Frequently asked questions
How many months is a horse pregnant?
About 11 months, or 340 days on average.
Can a mare be overdue?
Gestations up to 370 days and longer can be normal if the mare is healthy. Ask your vet to check her if she passes 360 days.
When should a mare be checked after breeding?
At 14 to 16 days by ultrasound, which is the best time to detect and manage twins.
What is the gestation period for a horse?
About 340 days, which is just over 11 months. A normal pregnancy can run from 320 to 370 days.
How soon should a foal stand after birth?
Within about one hour, and nurse within about two hours. Many vets advise a check of mare and foal in the first day, so ask yours.
Reference charts
- Cow Gestation Chart
- Horse Gestation Chart
- Goat Gestation Chart
- Sheep Gestation Chart
- Animal Gestation Periods Chart
- Elephant Gestation Period
- Foaling Season Guide
More gestation calculators
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Calving date by breed, with the normal window.
Goat Gestation Calculator
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Sheep Gestation Calculator
Lambing date for ewes, with the normal window.
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Whelping date with week-by-week milestones.
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Rabbit Gestation Calculator
Kindling date and nest box date.