How it works
Mares carry a foal for about 340 days, roughly 11 months. The normal range is wide, about 320 to 370 days. Many mares foal later than the calendar says, and a mare often repeats her own timing from year to year. Donkeys carry about a year.
How to use it
Enter the last date she was covered or inseminated. If she ran with the stallion, add the day they were separated. Keep notes on each mare's actual foaling day, because her past pregnancies are the best guide.
Reference chart
| Type | Average gestation |
|---|---|
| Average horse | 340 days |
| Miniature horse | 330 days |
| Donkey / jenny | 365 days |
Frequently asked questions
How long is a horse pregnant?
About 340 days, or roughly 11 months. The normal range is about 320 to 370 days, so the due date is a guide rather than a deadline.
Is it normal for a mare to go past her due date?
Yes. Many healthy mares foal after 340 days, some well past 360. If she's past her date and you're worried, or she shows discharge or illness, call your vet.
When can you tell if a mare is pregnant?
A vet can usually see the pregnancy by ultrasound from about 14–16 days. That early check is also when twins are found and managed.
What are the signs a mare is about to foal?
In the last few weeks the udder fills. In the last day or two you'll often see wax on the teats and a relaxed tailhead and vulva. Many mares foal at night.
Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian. Last reviewed 2026-09-18.