Resources · Calculators · Equine
Horse and donkey gestation calculator
Horse gestation runs about 340 days. Donkeys run longer — roughly a year (~365 days). Punch the cover date and get a foaling due window, not a cow calendar.
We keep donkeys on this place (Virgil and Zander came from TMR Rescue). Donkey gestation is not 283-day beef math — plan closer to 12 months and give yourself a window, not one magic day. Horses default near 340 days; change the length if your vet or breed book says otherwise. Cattle dates live on the calving calculator. Watch the jacks on the ranch cam.
Worked example: donkey cover to a foaling window
Set Animal to Donkey and I have to Cover / breeding date → foal. Cover date 2026-04-15 at the default 365 days lands on 2027-04-15. The tool’s window is 2027-03-26 (345 days) through 2027-05-10 (390 days). Example only — punch your cover date in the calculator.
Same cover date, horse contrast
Leave the cover on 2026-04-15 and switch Animal to Horse at 340 days. Planning due date is 2027-03-21. The window runs 2027-03-01 (320 days) through 2027-04-20 (370 days). A jenny runs longer than a mare. Neither number is a cow. Cattle 283 lives on the calving calculator.
A watch window, not one magic day
Individuals vary. Treat the date as a window you watch, not a guaranteed foaling hour. If your vet or breed book uses a different length, fill Override days. To plan backward, switch I have to Target foal date → breed-by and enter the day you want the foal.
After you have a due window
A late jenny in East Texas heat still has to drink. Size the tank on the livestock water calculator. Condition on a donkey is its own chart — use donkey condition, not a beef score. Cow dates stay on calving.
Questions
How long is a donkey pregnant?
About 12 months (~365 days), longer than a horse. Use the donkey setting in the calculator.
How long is a horse pregnant?
About 340 days on average. Breed and individual mares vary — treat the date as a window.
Can I use a cattle gestation calculator for a jenny?
No. Cattle default 283 days. Use this horse/donkey tool instead.
How do I calculate a donkey foaling due date?
Choose Donkey (~365 days), Cover / breeding date → foal, enter the cover date, Calculate. You’ll get a planning due date plus an early/late window — not one guaranteed day.
What’s the difference between horse and donkey gestation?
Horses average about 340 days (often ~320–370). Donkeys / jennets average about 365 days and often run 11–13 months. Use the matching Animal setting.
Can I plan backward from a target foal date?
Yes — use Target foal date → breed-by to see when to cover if you want a foal around a chosen date.
What about mules or ponies?
Mule default ~345 days; pony ~330. Override days if your vet or breed reference differs.
Is this a pregnancy diagnosis?
No. Planning only off typical gestation lengths. Confirm with your vet.
Planning only. Horse ~340 days (often 320–370). Donkey/jennet ~365, and plenty go 11–13 months. Not a pregnancy diagnosis.
Words used here
All calculators Tools Glossary Conversion tools Field sheets Hay Stocking Calving Breakeven Fence 205-day Freezer beef Bale wt TDN cost Water Tape wt Cows/bull Make vs buy Board-feet Pond Foaling Eggs Frost dates Food plot