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Horse Gestation Calculator & Chart

Mares carry a foal for about 340 days (a little over 11 months), but horses have the widest normal range in common livestock: anywhere from 320 to 370 days can be normal. Foals born before 320 days are considered premature. Mares foaling early in the year often carry longer than mares foaling in summer.

Printable horses gestation chart (340-day average)

Print this and tack it by the breeding pen — or use the free HerdFlo app to get the exact date for any breeding, breed-adjusted, with calendar reminders.

BredFoaling
Jan 1Dec 7
Jan 8Dec 14
Jan 15Dec 21
Jan 22Dec 28
Jan 31Jan 6 *
Feb 1Jan 7 *
Feb 8Jan 14 *
Feb 15Jan 21 *
Feb 22Jan 28 *
Feb 28Feb 3 *
Mar 1Feb 4 *
Mar 8Feb 11 *
Mar 15Feb 18 *
Mar 22Feb 25 *
Mar 31Mar 6 *
Apr 1Mar 7 *
Apr 8Mar 14 *
Apr 15Mar 21 *
Apr 22Mar 28 *
Apr 30Apr 5 *
May 1Apr 6 *
May 8Apr 13 *
May 15Apr 20 *
May 22Apr 27 *
May 31May 6 *
Jun 1May 7 *
Jun 8May 14 *
Jun 15May 21 *
Jun 22May 28 *
Jun 30Jun 5 *
Jul 1Jun 6 *
Jul 8Jun 13 *
Jul 15Jun 20 *
Jul 22Jun 27 *
Jul 31Jul 6 *
Aug 1Jul 7 *
Aug 8Jul 14 *
Aug 15Jul 21 *
Aug 22Jul 28 *
Aug 31Aug 6 *
Sep 1Aug 7 *
Sep 8Aug 14 *
Sep 15Aug 21 *
Sep 22Aug 28 *
Sep 30Sep 5 *
Oct 1Sep 6 *
Oct 8Sep 13 *
Oct 15Sep 20 *
Oct 22Sep 27 *
Oct 31Oct 6 *
Nov 1Oct 7 *
Nov 8Oct 14 *
Nov 15Oct 21 *
Nov 22Oct 28 *
Nov 30Nov 5 *
Dec 1Nov 6 *
Dec 8Nov 13 *
Dec 15Nov 20 *
Dec 22Nov 27 *
Dec 31Dec 6 *

* lands in the following calendar year. Table uses the 340-day average; individual animals vary (320–370 days, and breed shifts it — use the calculator above for breed-specific dates).

Common questions

How long is a mare pregnant?

About 340 days on average — just over 11 months — but anywhere from roughly 320 to 370 days falls within the normal range. Individual mares are surprisingly consistent year to year.

When should the first pregnancy ultrasound happen?

Around 14–16 days after breeding, which also lets the vet check for twins while something can still be done about it. A re-check around 45–60 days is standard practice.

What is a red-bag delivery?

A premature separation of the placenta at foaling — the “red bag” appears instead of the normal white-blue membrane. It is an emergency: the foal must be delivered within minutes. Call your vet immediately.

When should I start watching the mare closely?

Begin nightly checks about two weeks before the due date. Udder fill, waxing of the teats, and relaxation of the croup muscles signal foaling is near.

Track the whole herd, not just one date

HerdFlo Pro adds animal records, breeding-to-calving tracking, weaning weights, and a treatment log with withdrawal dates. Join the launch list in the free app.

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