How Long Are Horses Pregnant?
335 to 340 days on average, about 11 months. But a normal pregnancy can be anywhere from 320 to 370 days, so plan for a window rather than a single date.
Calculate a foaling date and window →
Why the range is so wide
Horse gestation varies more than in cattle or sheep. University of Nebraska extension material gives an average of 335 to 340 days with a normal range of 320 to 370, and notes that colts tend to be carried 2 to 7 days longer than fillies.
Planning around the window
- Use the 340-day date as your reference, but be ready from the start of the window.
- Keep your vet's number handy and ask them which signs of foaling to watch for in your mare.
- Add the dates to your phone with the calendar download on the horse gestation calculator.
Source
Last reviewed 2026-10-21. Not veterinary advice.