Horse pregnancy guide
How long is a horse pregnant?
A horse is pregnant for about 340 days (about 11.2 months). The normal range is 320 to 365 days, so most foal arrive within that window rather than on the exact average day. Breed shifts the date by a few days, which is why the calculator asks for it.
Quick rule: Count about 11 months forward from the last breeding date, then adjust for breed.
How to use the horse pregnancy calculator
1. Enter the last breeding date. The last date she was covered or inseminated. If your vet confirmed ovulation, use that date. Tap Use today if it was today.
2. Pick the breed. The whole window moves with the breed average.
Then follow the schedule. Each task gets a real date, the next one is highlighted, the status shows whether your mare is on track, and the month by month cards above show where things stand. Use Copy schedule or Add to Google Calendar to keep it.
Gestation formulas
- Estimated foaling date = last breeding date + 340 days
- Earliest normal foaling = last breeding date + 320 days
- Latest normal foaling = last breeding date + 365 days
- Breed adjustment = breed average minus 340 days, applied to the whole window
- Call your vet if nothing has happened by day 370
Care schedule for a pregnant mare
| When | Task | Why |
|---|---|---|
| Day 15 | First ultrasound, twin check | Scan between days 14 to 16 to confirm pregnancy and check for twins. |
| Day 28 | Heartbeat check | Ultrasound around days 25 to 30 confirms a heartbeat. |
| Day 60 | Recheck pregnancy | A check around days 45 to 60 confirms she is still in foal. |
| Day 150 | EHV-1 vaccine, month 5 | Rhino abortion vaccine at months 5, 7 and 9, as your vet advises. |
| Day 210 | EHV-1 vaccine, month 7 | Second dose of the pregnancy EHV-1 schedule. |
| Day 270 | EHV-1 vaccine, month 9 | Third dose of the pregnancy EHV-1 schedule. |
| 35 days before due date | Pre-foaling vaccine boosters | Core boosters 4 to 6 weeks before foaling pass immunity to the foal through colostrum. |
| 28 days before due date | Move to foaling area | Clean, roomy stall or paddock. Ask your farrier about removing hind shoes. |
| 14 days before due date | Watch for udder changes | The udder fills and teats may wax 1 to 4 days before foaling. |
Signs of foaling and when to call the vet
Labour is close if she has
- ✓Udder fills and teats wax over
- ✓Muscles around the tailhead soften
- ✓Sweating, pacing, looking at her flanks
- ✓Waters break, then the foal should arrive within 30 minutes
Call your vet immediately if
- !Strong straining for 30 minutes with no foal born
- !A baby is visible but stuck, or comes backwards with no progress
- !Heavy bleeding or foul-smelling discharge
- !She is weak, collapsed, off her food or in obvious pain
- !No foaling by day 370
Horse gestation by breed
| Breed or type | Average | Normal window from the start date |
|---|---|---|
| Light horse, Quarter Horse, Thoroughbred, Arabian | 340 days | 320 to 365 days |
| Warmblood | 342 days | 322 to 367 days |
| Draft horse | 345 days | 325 to 370 days |
| Pony | 335 days | 315 to 360 days |
| Miniature horse | 330 days | 310 to 355 days |
Frequently asked questions
How long is a horse pregnant?
A horse is pregnant for about 340 days (about 11.2 months). Most foal arrive between day 320 and day 365. Breed matters: Light horse, Quarter Horse, Thoroughbred, Arabian about 340 days, Warmblood about 342 days, Draft horse about 345 days, Pony about 335 days.
How accurate is this calculator?
It uses the average length and the normal range published in veterinary references, adjusted for the breed you pick. Individual animals vary, so treat the date as the middle of a window, not a promise.
When can I confirm the pregnancy?
First ultrasound, twin check around day 15. Scan between days 14 to 16 to confirm pregnancy and check for twins.
What if she goes past the due date?
Going a few days past the average is normal. The calculator marks day 365 as the end of the usual window and day 370 as the point to call your vet even if she seems well.
What are the signs that foaling is close?
Udder fills and teats wax over. Muscles around the tailhead soften. Sweating, pacing, looking at her flanks.
Is my data saved?
No. Everything is calculated in your browser. Nothing you type is stored or sent anywhere.
Disclaimer: This calculator gives estimates for planning only. It is not veterinary advice and cannot replace an examination by your vet. If you are worried at any stage, especially around birth, contact your vet promptly.
