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Horse Gestation Calculator

Type the day your mare was bred. Get her foaling date and the normal range.

1Animal

2Breeding

How she was bred

The last day she was bred or covered.

Due date

October 2, 2027Saturday

  • 338days, on average
  • Sep 14 to Nov 3normal range
  • 338days to go
  • Your mare should foal on Saturday, October 2, 2027. That is 338 days after she was bred.
  • The normal range is Sep 14 to Nov 3.
  • Watch her for heat on Nov 19 and Dec 10. If she comes into heat, she is not bred.
  • Next: Nov 12. First ultrasound check, days 14 to 16.
  • Today she is on day 0. 338 days to go.

Due Oct 2Answer

Her calendar

    When she is close

    • Her udder fills 2 to 6 weeks before she foals.
    • Her hind end relaxes in the last 7 to 14 days.
    • Milk fills her teats 4 to 6 days before.
    • Wax shows on her teats 1 to 2 days before.
    • Hard labor and the birth usually take 10 to 30 minutes.

    Call your vet if

    • Hard labor goes on more than 20 minutes after her water breaks.

    Your herd

    Keep a list of your mares and their due dates. Type a tag or a name, then add her. The list stays in this browser only.

    Gestation by animal

    Due dates are for the date you typed above: October 29, 2026.

    AnimalAverageSpreadDue dateSource
    Horse338 days 320 to 370 days (normal range) Oct 2 Nebraska Extension G1874
    Donkey371 days 354 to 387 days (2 in 3) Nov 4 Theriogenology

    Horse gestation chart

    Find the day she was bred. Next to it is her due date. This chart is for Horse, bred in 2026.

    January

    1. 1Dec 5
    2. 2Dec 6
    3. 3Dec 7
    4. 4Dec 8
    5. 5Dec 9
    6. 6Dec 10
    7. 7Dec 11
    8. 8Dec 12
    9. 9Dec 13
    10. 10Dec 14
    11. 11Dec 15
    12. 12Dec 16
    13. 13Dec 17
    14. 14Dec 18
    15. 15Dec 19
    16. 16Dec 20
    17. 17Dec 21
    18. 18Dec 22
    19. 19Dec 23
    20. 20Dec 24
    21. 21Dec 25
    22. 22Dec 26
    23. 23Dec 27
    24. 24Dec 28
    25. 25Dec 29
    26. 26Dec 30
    27. 27Dec 31
    28. 28Jan 1
    29. 29Jan 2
    30. 30Jan 3
    31. 31Jan 4

    February

    1. 1Jan 5
    2. 2Jan 6
    3. 3Jan 7
    4. 4Jan 8
    5. 5Jan 9
    6. 6Jan 10
    7. 7Jan 11
    8. 8Jan 12
    9. 9Jan 13
    10. 10Jan 14
    11. 11Jan 15
    12. 12Jan 16
    13. 13Jan 17
    14. 14Jan 18
    15. 15Jan 19
    16. 16Jan 20
    17. 17Jan 21
    18. 18Jan 22
    19. 19Jan 23
    20. 20Jan 24
    21. 21Jan 25
    22. 22Jan 26
    23. 23Jan 27
    24. 24Jan 28
    25. 25Jan 29
    26. 26Jan 30
    27. 27Jan 31
    28. 28Feb 1

    March

    1. 1Feb 2
    2. 2Feb 3
    3. 3Feb 4
    4. 4Feb 5
    5. 5Feb 6
    6. 6Feb 7
    7. 7Feb 8
    8. 8Feb 9
    9. 9Feb 10
    10. 10Feb 11
    11. 11Feb 12
    12. 12Feb 13
    13. 13Feb 14
    14. 14Feb 15
    15. 15Feb 16
    16. 16Feb 17
    17. 17Feb 18
    18. 18Feb 19
    19. 19Feb 20
    20. 20Feb 21
    21. 21Feb 22
    22. 22Feb 23
    23. 23Feb 24
    24. 24Feb 25
    25. 25Feb 26
    26. 26Feb 27
    27. 27Feb 28
    28. 28Mar 1
    29. 29Mar 2
    30. 30Mar 3
    31. 31Mar 4

    April

    1. 1Mar 5
    2. 2Mar 6
    3. 3Mar 7
    4. 4Mar 8
    5. 5Mar 9
    6. 6Mar 10
    7. 7Mar 11
    8. 8Mar 12
    9. 9Mar 13
    10. 10Mar 14
    11. 11Mar 15
    12. 12Mar 16
    13. 13Mar 17
    14. 14Mar 18
    15. 15Mar 19
    16. 16Mar 20
    17. 17Mar 21
    18. 18Mar 22
    19. 19Mar 23
    20. 20Mar 24
    21. 21Mar 25
    22. 22Mar 26
    23. 23Mar 27
    24. 24Mar 28
    25. 25Mar 29
    26. 26Mar 30
    27. 27Mar 31
    28. 28Apr 1
    29. 29Apr 2
    30. 30Apr 3

    May

    1. 1Apr 4
    2. 2Apr 5
    3. 3Apr 6
    4. 4Apr 7
    5. 5Apr 8
    6. 6Apr 9
    7. 7Apr 10
    8. 8Apr 11
    9. 9Apr 12
    10. 10Apr 13
    11. 11Apr 14
    12. 12Apr 15
    13. 13Apr 16
    14. 14Apr 17
    15. 15Apr 18
    16. 16Apr 19
    17. 17Apr 20
    18. 18Apr 21
    19. 19Apr 22
    20. 20Apr 23
    21. 21Apr 24
    22. 22Apr 25
    23. 23Apr 26
    24. 24Apr 27
    25. 25Apr 28
    26. 26Apr 29
    27. 27Apr 30
    28. 28May 1
    29. 29May 2
    30. 30May 3
    31. 31May 4

    June

    1. 1May 5
    2. 2May 6
    3. 3May 7
    4. 4May 8
    5. 5May 9
    6. 6May 10
    7. 7May 11
    8. 8May 12
    9. 9May 13
    10. 10May 14
    11. 11May 15
    12. 12May 16
    13. 13May 17
    14. 14May 18
    15. 15May 19
    16. 16May 20
    17. 17May 21
    18. 18May 22
    19. 19May 23
    20. 20May 24
    21. 21May 25
    22. 22May 26
    23. 23May 27
    24. 24May 28
    25. 25May 29
    26. 26May 30
    27. 27May 31
    28. 28Jun 1
    29. 29Jun 2
    30. 30Jun 3

    July

    1. 1Jun 4
    2. 2Jun 5
    3. 3Jun 6
    4. 4Jun 7
    5. 5Jun 8
    6. 6Jun 9
    7. 7Jun 10
    8. 8Jun 11
    9. 9Jun 12
    10. 10Jun 13
    11. 11Jun 14
    12. 12Jun 15
    13. 13Jun 16
    14. 14Jun 17
    15. 15Jun 18
    16. 16Jun 19
    17. 17Jun 20
    18. 18Jun 21
    19. 19Jun 22
    20. 20Jun 23
    21. 21Jun 24
    22. 22Jun 25
    23. 23Jun 26
    24. 24Jun 27
    25. 25Jun 28
    26. 26Jun 29
    27. 27Jun 30
    28. 28Jul 1
    29. 29Jul 2
    30. 30Jul 3
    31. 31Jul 4

    August

    1. 1Jul 5
    2. 2Jul 6
    3. 3Jul 7
    4. 4Jul 8
    5. 5Jul 9
    6. 6Jul 10
    7. 7Jul 11
    8. 8Jul 12
    9. 9Jul 13
    10. 10Jul 14
    11. 11Jul 15
    12. 12Jul 16
    13. 13Jul 17
    14. 14Jul 18
    15. 15Jul 19
    16. 16Jul 20
    17. 17Jul 21
    18. 18Jul 22
    19. 19Jul 23
    20. 20Jul 24
    21. 21Jul 25
    22. 22Jul 26
    23. 23Jul 27
    24. 24Jul 28
    25. 25Jul 29
    26. 26Jul 30
    27. 27Jul 31
    28. 28Aug 1
    29. 29Aug 2
    30. 30Aug 3
    31. 31Aug 4

    September

    1. 1Aug 5
    2. 2Aug 6
    3. 3Aug 7
    4. 4Aug 8
    5. 5Aug 9
    6. 6Aug 10
    7. 7Aug 11
    8. 8Aug 12
    9. 9Aug 13
    10. 10Aug 14
    11. 11Aug 15
    12. 12Aug 16
    13. 13Aug 17
    14. 14Aug 18
    15. 15Aug 19
    16. 16Aug 20
    17. 17Aug 21
    18. 18Aug 22
    19. 19Aug 23
    20. 20Aug 24
    21. 21Aug 25
    22. 22Aug 26
    23. 23Aug 27
    24. 24Aug 28
    25. 25Aug 29
    26. 26Aug 30
    27. 27Aug 31
    28. 28Sep 1
    29. 29Sep 2
    30. 30Sep 3

    October

    1. 1Sep 4
    2. 2Sep 5
    3. 3Sep 6
    4. 4Sep 7
    5. 5Sep 8
    6. 6Sep 9
    7. 7Sep 10
    8. 8Sep 11
    9. 9Sep 12
    10. 10Sep 13
    11. 11Sep 14
    12. 12Sep 15
    13. 13Sep 16
    14. 14Sep 17
    15. 15Sep 18
    16. 16Sep 19
    17. 17Sep 20
    18. 18Sep 21
    19. 19Sep 22
    20. 20Sep 23
    21. 21Sep 24
    22. 22Sep 25
    23. 23Sep 26
    24. 24Sep 27
    25. 25Sep 28
    26. 26Sep 29
    27. 27Sep 30
    28. 28Oct 1
    29. 29Oct 2
    30. 30Oct 3
    31. 31Oct 4

    November

    1. 1Oct 5
    2. 2Oct 6
    3. 3Oct 7
    4. 4Oct 8
    5. 5Oct 9
    6. 6Oct 10
    7. 7Oct 11
    8. 8Oct 12
    9. 9Oct 13
    10. 10Oct 14
    11. 11Oct 15
    12. 12Oct 16
    13. 13Oct 17
    14. 14Oct 18
    15. 15Oct 19
    16. 16Oct 20
    17. 17Oct 21
    18. 18Oct 22
    19. 19Oct 23
    20. 20Oct 24
    21. 21Oct 25
    22. 22Oct 26
    23. 23Oct 27
    24. 24Oct 28
    25. 25Oct 29
    26. 26Oct 30
    27. 27Oct 31
    28. 28Nov 1
    29. 29Nov 2
    30. 30Nov 3

    December

    1. 1Nov 4
    2. 2Nov 5
    3. 3Nov 6
    4. 4Nov 7
    5. 5Nov 8
    6. 6Nov 9
    7. 7Nov 10
    8. 8Nov 11
    9. 9Nov 12
    10. 10Nov 13
    11. 11Nov 14
    12. 12Nov 15
    13. 13Nov 16
    14. 14Nov 17
    15. 15Nov 18
    16. 16Nov 19
    17. 17Nov 20
    18. 18Nov 21
    19. 19Nov 22
    20. 20Nov 23
    21. 21Nov 24
    22. 22Nov 25
    23. 23Nov 26
    24. 24Nov 27
    25. 25Nov 28
    26. 26Nov 29
    27. 27Nov 30
    28. 28Dec 1
    29. 29Dec 2
    30. 30Dec 3
    31. 31Dec 4

    Why the range is so wide

    Mares carry their foals for very different lengths of time. A normal pregnancy can be 320 days or 370 days. That is almost 2 months apart.

    So the due date is only the middle. Watch your mare from about day 320 on.

    Colts are carried 2 to 7 days longer than fillies.

    Donkeys

    Pick Donkey above. Jennies carry longer than mares: about 371 days in a study of 28 jennies. In that study, the spread was about 17 days each way.

    We do not show heat days for donkeys, because our sources do not give a donkey heat cycle.

    Questions

    How long is a horse pregnant?

    About 335 to 340 days on average, or 11 months. A normal pregnancy can be 320 to 370 days.

    Is my mare overdue?

    Not if it is less than 370 days. A normal pregnancy can last that long. Ask your vet if you are worried, or if she shows signs of trouble.

    When is a foal born too early?

    A foal born before 326 days is called premature.

    Do colts take longer than fillies?

    Yes. Colts are carried 2 to 7 days longer than fillies.

    How long is a donkey pregnant?

    About 371 days in one study of 28 jennies, give or take 17 days. The Merck Veterinary Manual says 365.

    Sources

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