Livestock Gestation Calculator
Enter a breeding date (or the due date you want) and a species to get the expected due date, the normal window, days remaining, and planning checkpoints.
Free · no account · works on mobile · embeddable
Best for small herds and flocks planning calving, kidding, lambing, farrowing, kindling, and foaling. Updated .
The breeding
Expected calving
Due date = breeding date + average gestation (283 days for cattle). The window adds the earliest and latest normal lengths. Averages differ by breed, age, and litter size, so use your own herd records once you have them, and talk to your veterinarian about anything outside the window.
About the livestock gestation calculator
Every species carries for a different length of time, and a due date is only useful with the window around it. This calculator takes a breeding date and a species and returns the average due date, the earliest and latest normal dates, how far along the animal is today, and the days left. Flip the mode and it works backward: enter the due date you want, for a spring kidding or a fall calf crop, and it tells you when to breed.
It is for cattle, goats, sheep, pigs, rabbits, horses, and alpacas or llamas, with a custom option for anything else, and it is built for small farms that keep a few breeding animals rather than a herd management program.
Gestation lengths the calculator uses
The presets come from extension sources. Cattle average 283 days, with a normal range of about 265 to 295 and a drift toward shorter pregnancies in breeds selected for calving ease. Goats and sheep both land near 150 days, with kidding and lambing generally between 147 and 155 days after conception; the calculator uses 150 for goats and 148 for sheep. Pigs are the famous 114 days, or 3 months, 3 weeks, and 3 days, with most sows farrowing between 110 and 117. Rabbits kindle at 31 to 32 days, 28 to 33 depending on breed size. Mares average 338 to 345 days with a normal range of 320 to 380. Alpacas and llamas run about 11.5 months, 350 days plus or minus 14; some sources put alpacas nearer 335, so enter your own herd's average with the custom option if it runs short.
Reading the window and the checkpoints
The green card is the average due date. The window under it is the span in which a normal birth is expected, so the start of the window is the date to begin watching closely, not the due date itself. Three species carry planning checkpoints that extension guidance supports: rabbits get a nest box placed 28 days after breeding, sows are commonly moved to the farrowing pen up to 10 days before the due date, and mares are put on close foaling watch from day 335. These are planning suggestions, not veterinary instructions.
Dates count from the day you enter. If a female was exposed to a male for a period rather than bred on one day, run the calculator for the first and last possible dates and plan around the full span.
Worked example: a cow bred May 1
Enter a breeding date of May 1, 2026 and the cattle preset (283 days), checked on September 4, 2026. The cow is due Monday, February 8, 2027, with a normal window from January 21 to February 20, 2027 (265 to 295 days). On September 4 she is 126 days along, 18.0 weeks and 44.5% of the way, with 157 days remaining. Working backward instead, a goat you want kidding on March 15, 2027 needs to be bred on or about October 16, 2026 (150 days), and the normal kidding window for that breeding runs March 12 to March 20, 2027.
Sources
- Ohio State University Extension, Beef Team, Gestation length: calves arrive sooner than they used to. Beef gestation averages 283 days and can range from about 265 to 295, shorter in breeds selected for low birth weight. Accessed Sep 4, 2026.
- Oklahoma State University Extension, Foaling management and care of the nursing foal. Mare gestation averages 338 to 345 days with a normal range of 320 to 380, and 335 days is the common trigger for close monitoring. Accessed Sep 4, 2026.
This calculator gives planning estimates from the numbers you enter. It is not accounting, tax, veterinary, or legal advice. Replace the defaults with your own farm records whenever you have them.
Frequently asked questions
How long is a cow pregnant?
About 283 days, a little over nine months, with normal calvings anywhere from roughly 265 to 295 days. Breeds selected for calving ease have been trending shorter; a recent Angus data set averaged under 279 days. Use your own herd's records if you have them.
How long are goats and sheep pregnant?
Around 150 days, or five months. Extension guidance puts kidding and lambing between 147 and 155 days after conception. Does carrying multiple kids often deliver a day or two early.
What is the gestation period of a pig?
114 days, remembered as 3 months, 3 weeks, and 3 days. Most sows farrow between 110 and 117 days. Sows are usually moved to farrowing quarters up to 10 days before the due date.
How do I work out when to breed for a specific due date?
Switch the calculator to the due-date mode, enter the date you want, and it subtracts the species' average gestation to give a breeding date. Count back a few more days if you want the birth before, rather than around, a fixed date such as a show or a market.
Why does the calculator show a window and not just one date?
Because normal gestation varies by breed, age of the dam, litter size, and the sex of the offspring. A cow can calve two weeks either side of 283 days and be perfectly normal. Start watching at the front of the window and call your veterinarian if the animal passes the back of it with no signs.
Related free tools
Add this calculator to your website
Copy the snippet into an HTML block. The calculator stays free and up to date; please keep the small Farmstand credit link.
<iframe src="https://thenewfarmstand.com/embed/tools/livestock-gestation-calculator" title="Livestock Gestation Calculator" width="100%" height="900" style="border:1px solid #dfe7dc;border-radius:16px;max-width:100%" loading="lazy"></iframe>
<p style="font:14px/1.5 system-ui,sans-serif">Powered by <a href="https://thenewfarmstand.com/tools/livestock-gestation-calculator">Livestock Gestation Calculator from The New Farmstand</a></p>No login, cookies, or Farmstand account required to use the embedded calculator.
Get practical farm-business tools in your inbox
Calculator updates and useful notes on forecasting, pricing, and direct sales. Your result is already yours; email is completely optional.
Ready to stop rebuilding the same farm spreadsheet?
Farmstand connects production forecasts, products, orders, subscriptions, customers, and farm records in one place.