The whole year: the day she was bred, and the day she is due.
Horses carry about 340 days — about 11 months. Find the day she was bred in the chart and read her due date beside it. Most horses have their foals from 20 days before to 30 days after that date (day 320 to day 370).
Counted 340 days from the breeding day, the way online calculators count. Some printed tables count the breeding day as day 1 and show one day earlier — both are inside her window.
In a year when February 29 falls between the breeding and the birth, her due date is one day earlier than the chart shows.
A common guide — your vet’s plan wins.
Bred on → due on
Bred in January
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
Jan 27
Jan 2
Jan 28
Jan 3
Jan 29
Jan 4
Jan 30
Jan 5
Jan 31
Jan 6
Bred in February
Bred
Due
Feb 1
Jan 7
Feb 2
Jan 8
Feb 3
Jan 9
Feb 4
Jan 10
Feb 5
Jan 11
Feb 6
Jan 12
Feb 7
Jan 13
Feb 8
Jan 14
Feb 9
Jan 15
Feb 10
Jan 16
Feb 11
Jan 17
Feb 12
Jan 18
Feb 13
Jan 19
Feb 14
Jan 20
Feb 15
Jan 21
Feb 16
Jan 22
Feb 17
Jan 23
Feb 18
Jan 24
Feb 19
Jan 25
Feb 20
Jan 26
Feb 21
Jan 27
Feb 22
Jan 28
Feb 23
Jan 29
Feb 24
Jan 30
Feb 25
Jan 31
Feb 26
Feb 1
Feb 27
Feb 2
Feb 28
Feb 3
Bred in March
Bred
Due
Mar 1
Feb 4
Mar 2
Feb 5
Mar 3
Feb 6
Mar 4
Feb 7
Mar 5
Feb 8
Mar 6
Feb 9
Mar 7
Feb 10
Mar 8
Feb 11
Mar 9
Feb 12
Mar 10
Feb 13
Mar 11
Feb 14
Mar 12
Feb 15
Mar 13
Feb 16
Mar 14
Feb 17
Mar 15
Feb 18
Mar 16
Feb 19
Mar 17
Feb 20
Mar 18
Feb 21
Mar 19
Feb 22
Mar 20
Feb 23
Mar 21
Feb 24
Mar 22
Feb 25
Mar 23
Feb 26
Mar 24
Feb 27
Mar 25
Feb 28
Mar 26
Mar 1
Mar 27
Mar 2
Mar 28
Mar 3
Mar 29
Mar 4
Mar 30
Mar 5
Mar 31
Mar 6
Bred in April
Bred
Due
Apr 1
Mar 7
Apr 2
Mar 8
Apr 3
Mar 9
Apr 4
Mar 10
Apr 5
Mar 11
Apr 6
Mar 12
Apr 7
Mar 13
Apr 8
Mar 14
Apr 9
Mar 15
Apr 10
Mar 16
Apr 11
Mar 17
Apr 12
Mar 18
Apr 13
Mar 19
Apr 14
Mar 20
Apr 15
Mar 21
Apr 16
Mar 22
Apr 17
Mar 23
Apr 18
Mar 24
Apr 19
Mar 25
Apr 20
Mar 26
Apr 21
Mar 27
Apr 22
Mar 28
Apr 23
Mar 29
Apr 24
Mar 30
Apr 25
Mar 31
Apr 26
Apr 1
Apr 27
Apr 2
Apr 28
Apr 3
Apr 29
Apr 4
Apr 30
Apr 5
Bred in May
Bred
Due
May 1
Apr 6
May 2
Apr 7
May 3
Apr 8
May 4
Apr 9
May 5
Apr 10
May 6
Apr 11
May 7
Apr 12
May 8
Apr 13
May 9
Apr 14
May 10
Apr 15
May 11
Apr 16
May 12
Apr 17
May 13
Apr 18
May 14
Apr 19
May 15
Apr 20
May 16
Apr 21
May 17
Apr 22
May 18
Apr 23
May 19
Apr 24
May 20
Apr 25
May 21
Apr 26
May 22
Apr 27
May 23
Apr 28
May 24
Apr 29
May 25
Apr 30
May 26
May 1
May 27
May 2
May 28
May 3
May 29
May 4
May 30
May 5
May 31
May 6
Bred in June
Bred
Due
Jun 1
May 7
Jun 2
May 8
Jun 3
May 9
Jun 4
May 10
Jun 5
May 11
Jun 6
May 12
Jun 7
May 13
Jun 8
May 14
Jun 9
May 15
Jun 10
May 16
Jun 11
May 17
Jun 12
May 18
Jun 13
May 19
Jun 14
May 20
Jun 15
May 21
Jun 16
May 22
Jun 17
May 23
Jun 18
May 24
Jun 19
May 25
Jun 20
May 26
Jun 21
May 27
Jun 22
May 28
Jun 23
May 29
Jun 24
May 30
Jun 25
May 31
Jun 26
Jun 1
Jun 27
Jun 2
Jun 28
Jun 3
Jun 29
Jun 4
Jun 30
Jun 5
Bred in July
Bred
Due
Jul 1
Jun 6
Jul 2
Jun 7
Jul 3
Jun 8
Jul 4
Jun 9
Jul 5
Jun 10
Jul 6
Jun 11
Jul 7
Jun 12
Jul 8
Jun 13
Jul 9
Jun 14
Jul 10
Jun 15
Jul 11
Jun 16
Jul 12
Jun 17
Jul 13
Jun 18
Jul 14
Jun 19
Jul 15
Jun 20
Jul 16
Jun 21
Jul 17
Jun 22
Jul 18
Jun 23
Jul 19
Jun 24
Jul 20
Jun 25
Jul 21
Jun 26
Jul 22
Jun 27
Jul 23
Jun 28
Jul 24
Jun 29
Jul 25
Jun 30
Jul 26
Jul 1
Jul 27
Jul 2
Jul 28
Jul 3
Jul 29
Jul 4
Jul 30
Jul 5
Jul 31
Jul 6
Bred in August
Bred
Due
Aug 1
Jul 7
Aug 2
Jul 8
Aug 3
Jul 9
Aug 4
Jul 10
Aug 5
Jul 11
Aug 6
Jul 12
Aug 7
Jul 13
Aug 8
Jul 14
Aug 9
Jul 15
Aug 10
Jul 16
Aug 11
Jul 17
Aug 12
Jul 18
Aug 13
Jul 19
Aug 14
Jul 20
Aug 15
Jul 21
Aug 16
Jul 22
Aug 17
Jul 23
Aug 18
Jul 24
Aug 19
Jul 25
Aug 20
Jul 26
Aug 21
Jul 27
Aug 22
Jul 28
Aug 23
Jul 29
Aug 24
Jul 30
Aug 25
Jul 31
Aug 26
Aug 1
Aug 27
Aug 2
Aug 28
Aug 3
Aug 29
Aug 4
Aug 30
Aug 5
Aug 31
Aug 6
Bred in September
Bred
Due
Sep 1
Aug 7
Sep 2
Aug 8
Sep 3
Aug 9
Sep 4
Aug 10
Sep 5
Aug 11
Sep 6
Aug 12
Sep 7
Aug 13
Sep 8
Aug 14
Sep 9
Aug 15
Sep 10
Aug 16
Sep 11
Aug 17
Sep 12
Aug 18
Sep 13
Aug 19
Sep 14
Aug 20
Sep 15
Aug 21
Sep 16
Aug 22
Sep 17
Aug 23
Sep 18
Aug 24
Sep 19
Aug 25
Sep 20
Aug 26
Sep 21
Aug 27
Sep 22
Aug 28
Sep 23
Aug 29
Sep 24
Aug 30
Sep 25
Aug 31
Sep 26
Sep 1
Sep 27
Sep 2
Sep 28
Sep 3
Sep 29
Sep 4
Sep 30
Sep 5
Bred in October
Bred
Due
Oct 1
Sep 6
Oct 2
Sep 7
Oct 3
Sep 8
Oct 4
Sep 9
Oct 5
Sep 10
Oct 6
Sep 11
Oct 7
Sep 12
Oct 8
Sep 13
Oct 9
Sep 14
Oct 10
Sep 15
Oct 11
Sep 16
Oct 12
Sep 17
Oct 13
Sep 18
Oct 14
Sep 19
Oct 15
Sep 20
Oct 16
Sep 21
Oct 17
Sep 22
Oct 18
Sep 23
Oct 19
Sep 24
Oct 20
Sep 25
Oct 21
Sep 26
Oct 22
Sep 27
Oct 23
Sep 28
Oct 24
Sep 29
Oct 25
Sep 30
Oct 26
Oct 1
Oct 27
Oct 2
Oct 28
Oct 3
Oct 29
Oct 4
Oct 30
Oct 5
Oct 31
Oct 6
Bred in November
Bred
Due
Nov 1
Oct 7
Nov 2
Oct 8
Nov 3
Oct 9
Nov 4
Oct 10
Nov 5
Oct 11
Nov 6
Oct 12
Nov 7
Oct 13
Nov 8
Oct 14
Nov 9
Oct 15
Nov 10
Oct 16
Nov 11
Oct 17
Nov 12
Oct 18
Nov 13
Oct 19
Nov 14
Oct 20
Nov 15
Oct 21
Nov 16
Oct 22
Nov 17
Oct 23
Nov 18
Oct 24
Nov 19
Oct 25
Nov 20
Oct 26
Nov 21
Oct 27
Nov 22
Oct 28
Nov 23
Oct 29
Nov 24
Oct 30
Nov 25
Oct 31
Nov 26
Nov 1
Nov 27
Nov 2
Nov 28
Nov 3
Nov 29
Nov 4
Nov 30
Nov 5
Bred in December
Bred
Due
Dec 1
Nov 6
Dec 2
Nov 7
Dec 3
Nov 8
Dec 4
Nov 9
Dec 5
Nov 10
Dec 6
Nov 11
Dec 7
Nov 12
Dec 8
Nov 13
Dec 9
Nov 14
Dec 10
Nov 15
Dec 11
Nov 16
Dec 12
Nov 17
Dec 13
Nov 18
Dec 14
Nov 19
Dec 15
Nov 20
Dec 16
Nov 21
Dec 17
Nov 22
Dec 18
Nov 23
Dec 19
Nov 24
Dec 20
Nov 25
Dec 21
Nov 26
Dec 22
Nov 27
Dec 23
Nov 28
Dec 24
Nov 29
Dec 25
Nov 30
Dec 26
Dec 1
Dec 27
Dec 2
Dec 28
Dec 3
Dec 29
Dec 4
Dec 30
Dec 5
Dec 31
Dec 6
Questions
How do I read a horse gestation chart?
Find the month and the day she was bred; the date beside it is her due date. A mare bred on January 1 is due about December 7.
Why is there a window around the due date?
No two horses are the same. Most give birth from 20 days before to 30 days after the date in the chart, so start watching her at the beginning of that window.
Why does another chart say one day earlier?
Counted 340 days from the breeding day, the way online calculators count. Some printed tables count the breeding day as day 1 and show one day earlier — both are inside her window.
What if she was with the stallion for weeks?
Read the chart for the first and the last day they were together: she is due between those two dates, give or take her window. The calculator does this for you.