Home › Horse Gestation Calculator Horse Gestation Calculator Mares carry a foal for 335 to 340 days on average, but anything from 320 to 370 days is normal. The calculator uses 340 days and shows the full window.
Horse due date calculator One breeding date Stallion in → stallion out Work back from foaling
Gestation length Standard (340 days) Short end of average (335 days) Custom length… Breeding date
Pick a date to see the due date.
How the calculator works It adds the gestation length to the date you enter, counting calendar days (including leap days). The default for horse is 340 days, and the result also shows a window of 320 to 370 days (normal range). Average is 335 to 340 days; colts tend to be carried 2 to 7 days longer than fillies. Change the length if your vet, breed society or sire information says otherwise. All calculations run in your browser; nothing you enter is sent anywhere.
Worked examples A mare covered on April 20, 2026, is due around March 26, 2027 , and could normally foal anywhere from March 6 to April 25. Horse gestation facts Average gestation 335 to 340 days Normal range 320 to 370 days Colts vs fillies Colts 2 to 7 days longer
Common questions Why is the foaling window so wide? Horse gestation varies more than in other livestock. University of Nebraska extension material gives a 320 to 370 day range, and notes colts tend to be carried 2 to 7 days longer than fillies.
When is a foal premature? Ask your veterinarian. Published cut-offs differ between sources, so the calculator does not label a date as premature.
Printable horse gestation chart Show the full foaling table for every breeding date of the year Breeding year 2025 2026 2027 2028 Gestation length Standard (340 days) Short end of average (335 days) Print this table
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Horse, 340-day gestation. Find the date the mare was bred in the left column; the expected foaling date is on the right.
Bred in January 2026 Bred Due Jan 1 Dec 7 Jan 2 Dec 8 Jan 3 Dec 9 Jan 4 Dec 10 Jan 5 Dec 11 Jan 6 Dec 12 Jan 7 Dec 13 Jan 8 Dec 14 Jan 9 Dec 15 Jan 10 Dec 16 Jan 11 Dec 17 Jan 12 Dec 18 Jan 13 Dec 19 Jan 14 Dec 20 Jan 15 Dec 21 Jan 16 Dec 22 Jan 17 Dec 23 Jan 18 Dec 24 Jan 19 Dec 25 Jan 20 Dec 26 Jan 21 Dec 27 Jan 22 Dec 28 Jan 23 Dec 29 Jan 24 Dec 30 Jan 25 Dec 31 Jan 26 Jan 1, 2027 Jan 27 Jan 2, 2027 Jan 28 Jan 3, 2027 Jan 29 Jan 4, 2027 Jan 30 Jan 5, 2027 Jan 31 Jan 6, 2027
Bred in February 2026 Bred Due Feb 1 Jan 7, 2027 Feb 2 Jan 8, 2027 Feb 3 Jan 9, 2027 Feb 4 Jan 10, 2027 Feb 5 Jan 11, 2027 Feb 6 Jan 12, 2027 Feb 7 Jan 13, 2027 Feb 8 Jan 14, 2027 Feb 9 Jan 15, 2027 Feb 10 Jan 16, 2027 Feb 11 Jan 17, 2027 Feb 12 Jan 18, 2027 Feb 13 Jan 19, 2027 Feb 14 Jan 20, 2027 Feb 15 Jan 21, 2027 Feb 16 Jan 22, 2027 Feb 17 Jan 23, 2027 Feb 18 Jan 24, 2027 Feb 19 Jan 25, 2027 Feb 20 Jan 26, 2027 Feb 21 Jan 27, 2027 Feb 22 Jan 28, 2027 Feb 23 Jan 29, 2027 Feb 24 Jan 30, 2027 Feb 25 Jan 31, 2027 Feb 26 Feb 1, 2027 Feb 27 Feb 2, 2027 Feb 28 Feb 3, 2027
Bred in March 2026 Bred Due Mar 1 Feb 4, 2027 Mar 2 Feb 5, 2027 Mar 3 Feb 6, 2027 Mar 4 Feb 7, 2027 Mar 5 Feb 8, 2027 Mar 6 Feb 9, 2027 Mar 7 Feb 10, 2027 Mar 8 Feb 11, 2027 Mar 9 Feb 12, 2027 Mar 10 Feb 13, 2027 Mar 11 Feb 14, 2027 Mar 12 Feb 15, 2027 Mar 13 Feb 16, 2027 Mar 14 Feb 17, 2027 Mar 15 Feb 18, 2027 Mar 16 Feb 19, 2027 Mar 17 Feb 20, 2027 Mar 18 Feb 21, 2027 Mar 19 Feb 22, 2027 Mar 20 Feb 23, 2027 Mar 21 Feb 24, 2027 Mar 22 Feb 25, 2027 Mar 23 Feb 26, 2027 Mar 24 Feb 27, 2027 Mar 25 Feb 28, 2027 Mar 26 Mar 1, 2027 Mar 27 Mar 2, 2027 Mar 28 Mar 3, 2027 Mar 29 Mar 4, 2027 Mar 30 Mar 5, 2027 Mar 31 Mar 6, 2027
Bred in April 2026 Bred Due Apr 1 Mar 7, 2027 Apr 2 Mar 8, 2027 Apr 3 Mar 9, 2027 Apr 4 Mar 10, 2027 Apr 5 Mar 11, 2027 Apr 6 Mar 12, 2027 Apr 7 Mar 13, 2027 Apr 8 Mar 14, 2027 Apr 9 Mar 15, 2027 Apr 10 Mar 16, 2027 Apr 11 Mar 17, 2027 Apr 12 Mar 18, 2027 Apr 13 Mar 19, 2027 Apr 14 Mar 20, 2027 Apr 15 Mar 21, 2027 Apr 16 Mar 22, 2027 Apr 17 Mar 23, 2027 Apr 18 Mar 24, 2027 Apr 19 Mar 25, 2027 Apr 20 Mar 26, 2027 Apr 21 Mar 27, 2027 Apr 22 Mar 28, 2027 Apr 23 Mar 29, 2027 Apr 24 Mar 30, 2027 Apr 25 Mar 31, 2027 Apr 26 Apr 1, 2027 Apr 27 Apr 2, 2027 Apr 28 Apr 3, 2027 Apr 29 Apr 4, 2027 Apr 30 Apr 5, 2027
Bred in May 2026 Bred Due May 1 Apr 6, 2027 May 2 Apr 7, 2027 May 3 Apr 8, 2027 May 4 Apr 9, 2027 May 5 Apr 10, 2027 May 6 Apr 11, 2027 May 7 Apr 12, 2027 May 8 Apr 13, 2027 May 9 Apr 14, 2027 May 10 Apr 15, 2027 May 11 Apr 16, 2027 May 12 Apr 17, 2027 May 13 Apr 18, 2027 May 14 Apr 19, 2027 May 15 Apr 20, 2027 May 16 Apr 21, 2027 May 17 Apr 22, 2027 May 18 Apr 23, 2027 May 19 Apr 24, 2027 May 20 Apr 25, 2027 May 21 Apr 26, 2027 May 22 Apr 27, 2027 May 23 Apr 28, 2027 May 24 Apr 29, 2027 May 25 Apr 30, 2027 May 26 May 1, 2027 May 27 May 2, 2027 May 28 May 3, 2027 May 29 May 4, 2027 May 30 May 5, 2027 May 31 May 6, 2027
Bred in June 2026 Bred Due Jun 1 May 7, 2027 Jun 2 May 8, 2027 Jun 3 May 9, 2027 Jun 4 May 10, 2027 Jun 5 May 11, 2027 Jun 6 May 12, 2027 Jun 7 May 13, 2027 Jun 8 May 14, 2027 Jun 9 May 15, 2027 Jun 10 May 16, 2027 Jun 11 May 17, 2027 Jun 12 May 18, 2027 Jun 13 May 19, 2027 Jun 14 May 20, 2027 Jun 15 May 21, 2027 Jun 16 May 22, 2027 Jun 17 May 23, 2027 Jun 18 May 24, 2027 Jun 19 May 25, 2027 Jun 20 May 26, 2027 Jun 21 May 27, 2027 Jun 22 May 28, 2027 Jun 23 May 29, 2027 Jun 24 May 30, 2027 Jun 25 May 31, 2027 Jun 26 Jun 1, 2027 Jun 27 Jun 2, 2027 Jun 28 Jun 3, 2027 Jun 29 Jun 4, 2027 Jun 30 Jun 5, 2027
Bred in July 2026 Bred Due Jul 1 Jun 6, 2027 Jul 2 Jun 7, 2027 Jul 3 Jun 8, 2027 Jul 4 Jun 9, 2027 Jul 5 Jun 10, 2027 Jul 6 Jun 11, 2027 Jul 7 Jun 12, 2027 Jul 8 Jun 13, 2027 Jul 9 Jun 14, 2027 Jul 10 Jun 15, 2027 Jul 11 Jun 16, 2027 Jul 12 Jun 17, 2027 Jul 13 Jun 18, 2027 Jul 14 Jun 19, 2027 Jul 15 Jun 20, 2027 Jul 16 Jun 21, 2027 Jul 17 Jun 22, 2027 Jul 18 Jun 23, 2027 Jul 19 Jun 24, 2027 Jul 20 Jun 25, 2027 Jul 21 Jun 26, 2027 Jul 22 Jun 27, 2027 Jul 23 Jun 28, 2027 Jul 24 Jun 29, 2027 Jul 25 Jun 30, 2027 Jul 26 Jul 1, 2027 Jul 27 Jul 2, 2027 Jul 28 Jul 3, 2027 Jul 29 Jul 4, 2027 Jul 30 Jul 5, 2027 Jul 31 Jul 6, 2027
Bred in August 2026 Bred Due Aug 1 Jul 7, 2027 Aug 2 Jul 8, 2027 Aug 3 Jul 9, 2027 Aug 4 Jul 10, 2027 Aug 5 Jul 11, 2027 Aug 6 Jul 12, 2027 Aug 7 Jul 13, 2027 Aug 8 Jul 14, 2027 Aug 9 Jul 15, 2027 Aug 10 Jul 16, 2027 Aug 11 Jul 17, 2027 Aug 12 Jul 18, 2027 Aug 13 Jul 19, 2027 Aug 14 Jul 20, 2027 Aug 15 Jul 21, 2027 Aug 16 Jul 22, 2027 Aug 17 Jul 23, 2027 Aug 18 Jul 24, 2027 Aug 19 Jul 25, 2027 Aug 20 Jul 26, 2027 Aug 21 Jul 27, 2027 Aug 22 Jul 28, 2027 Aug 23 Jul 29, 2027 Aug 24 Jul 30, 2027 Aug 25 Jul 31, 2027 Aug 26 Aug 1, 2027 Aug 27 Aug 2, 2027 Aug 28 Aug 3, 2027 Aug 29 Aug 4, 2027 Aug 30 Aug 5, 2027 Aug 31 Aug 6, 2027
Bred in September 2026 Bred Due Sep 1 Aug 7, 2027 Sep 2 Aug 8, 2027 Sep 3 Aug 9, 2027 Sep 4 Aug 10, 2027 Sep 5 Aug 11, 2027 Sep 6 Aug 12, 2027 Sep 7 Aug 13, 2027 Sep 8 Aug 14, 2027 Sep 9 Aug 15, 2027 Sep 10 Aug 16, 2027 Sep 11 Aug 17, 2027 Sep 12 Aug 18, 2027 Sep 13 Aug 19, 2027 Sep 14 Aug 20, 2027 Sep 15 Aug 21, 2027 Sep 16 Aug 22, 2027 Sep 17 Aug 23, 2027 Sep 18 Aug 24, 2027 Sep 19 Aug 25, 2027 Sep 20 Aug 26, 2027 Sep 21 Aug 27, 2027 Sep 22 Aug 28, 2027 Sep 23 Aug 29, 2027 Sep 24 Aug 30, 2027 Sep 25 Aug 31, 2027 Sep 26 Sep 1, 2027 Sep 27 Sep 2, 2027 Sep 28 Sep 3, 2027 Sep 29 Sep 4, 2027 Sep 30 Sep 5, 2027
Bred in October 2026 Bred Due Oct 1 Sep 6, 2027 Oct 2 Sep 7, 2027 Oct 3 Sep 8, 2027 Oct 4 Sep 9, 2027 Oct 5 Sep 10, 2027 Oct 6 Sep 11, 2027 Oct 7 Sep 12, 2027 Oct 8 Sep 13, 2027 Oct 9 Sep 14, 2027 Oct 10 Sep 15, 2027 Oct 11 Sep 16, 2027 Oct 12 Sep 17, 2027 Oct 13 Sep 18, 2027 Oct 14 Sep 19, 2027 Oct 15 Sep 20, 2027 Oct 16 Sep 21, 2027 Oct 17 Sep 22, 2027 Oct 18 Sep 23, 2027 Oct 19 Sep 24, 2027 Oct 20 Sep 25, 2027 Oct 21 Sep 26, 2027 Oct 22 Sep 27, 2027 Oct 23 Sep 28, 2027 Oct 24 Sep 29, 2027 Oct 25 Sep 30, 2027 Oct 26 Oct 1, 2027 Oct 27 Oct 2, 2027 Oct 28 Oct 3, 2027 Oct 29 Oct 4, 2027 Oct 30 Oct 5, 2027 Oct 31 Oct 6, 2027
Bred in November 2026 Bred Due Nov 1 Oct 7, 2027 Nov 2 Oct 8, 2027 Nov 3 Oct 9, 2027 Nov 4 Oct 10, 2027 Nov 5 Oct 11, 2027 Nov 6 Oct 12, 2027 Nov 7 Oct 13, 2027 Nov 8 Oct 14, 2027 Nov 9 Oct 15, 2027 Nov 10 Oct 16, 2027 Nov 11 Oct 17, 2027 Nov 12 Oct 18, 2027 Nov 13 Oct 19, 2027 Nov 14 Oct 20, 2027 Nov 15 Oct 21, 2027 Nov 16 Oct 22, 2027 Nov 17 Oct 23, 2027 Nov 18 Oct 24, 2027 Nov 19 Oct 25, 2027 Nov 20 Oct 26, 2027 Nov 21 Oct 27, 2027 Nov 22 Oct 28, 2027 Nov 23 Oct 29, 2027 Nov 24 Oct 30, 2027 Nov 25 Oct 31, 2027 Nov 26 Nov 1, 2027 Nov 27 Nov 2, 2027 Nov 28 Nov 3, 2027 Nov 29 Nov 4, 2027 Nov 30 Nov 5, 2027
Bred in December 2026 Bred Due Dec 1 Nov 6, 2027 Dec 2 Nov 7, 2027 Dec 3 Nov 8, 2027 Dec 4 Nov 9, 2027 Dec 5 Nov 10, 2027 Dec 6 Nov 11, 2027 Dec 7 Nov 12, 2027 Dec 8 Nov 13, 2027 Dec 9 Nov 14, 2027 Dec 10 Nov 15, 2027 Dec 11 Nov 16, 2027 Dec 12 Nov 17, 2027 Dec 13 Nov 18, 2027 Dec 14 Nov 19, 2027 Dec 15 Nov 20, 2027 Dec 16 Nov 21, 2027 Dec 17 Nov 22, 2027 Dec 18 Nov 23, 2027 Dec 19 Nov 24, 2027 Dec 20 Nov 25, 2027 Dec 21 Nov 26, 2027 Dec 22 Nov 27, 2027 Dec 23 Nov 28, 2027 Dec 24 Nov 29, 2027 Dec 25 Nov 30, 2027 Dec 26 Dec 1, 2027 Dec 27 Dec 2, 2027 Dec 28 Dec 3, 2027 Dec 29 Dec 4, 2027 Dec 30 Dec 5, 2027 Dec 31 Dec 6, 2027
Related tools Sources
Last reviewed 2026-10-21. Planning tool only. Confirm pregnancies and due dates with your veterinarian. See methodology .