Cow Gestation Calculator
A cow is pregnant for about 283 days, a little over nine months. Enter a breeding or AI date for a calving date, enter the dates the bull went in and came out for the whole calving window, or start from when you want calving to begin to find your bull turnout date.
Cattle due date calculator
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 cattle is 283 days, and the result also shows a window of 253 to 300 days (shortest to longest recorded). Shortest and longest gestations recorded in a 10,037-record study of AI-bred beef cows (Journal of Animal Science abstract, 2024). 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 cow bred by AI on May 1, 2026, using the standard 283 days, is due on February 8, 2027. If she is not pregnant, expect her back in heat around May 22.
- Bulls in on May 15 and out on July 15, 2026 (a 62-day season) means calving from about February 22 to April 24, 2027, split into three 21-day periods.
Cattle gestation facts
| Typical gestation | 283 days (common standard); 280 days in a 2024 study of AI-bred beef cows |
|---|---|
| Breed averages (sire breed) | About 281 (Holstein) to 291 days (Brahman) |
| Longest / shortest recorded (2024 study) | 253 to 300 days |
| Heat cycle | 21 days (18 to 24) |
| Earliest pregnancy check | Ultrasound 28 days; blood test 25 (heifers) / 28 (cows) days |
Common questions
Why does the calculator let me change the gestation length?
283 days is the figure most charts use, but breeds differ. In a USDA Meat Animal Research Center comparison, calves sired by Holstein bulls averaged 281 days and Brahman-sired calves 291 days. A 2024 study of more than 10,000 AI-bred beef cows found an average of 280 days. Pick a breed preset or enter your own number. If your sire has a gestation-length EPD, you can use it to adjust the length.
Do bull calves take longer?
Slightly. In the 2024 study above, bull calves were carried 280.8 days on average and heifer calves 279.6 days. Fall-calving cows also averaged about two days shorter than spring-calving cows.
When can I preg-check?
Nebraska Extension gives ultrasound from about 28 days after breeding, blood tests from 25 days for heifers and 28 days for cows, and rectal palpation from 35 to 50 days in experienced hands. The calculator shows these dates under the result.
What are the 21-day calving periods?
A cow cycles about every 21 days (range 18 to 24). Splitting the calving season into 21-day periods shows how many cows settled on their first, second or third heat with the bull. Use the breeding season planner to do this for a whole herd.
Related tools
- Printable cattle gestation chart
- Breeding season planner (whole herd)
- Heat cycle calculator
- How long are cows pregnant?
Sources
- Drovers / Oklahoma State University: Is 283 days the accurate average gestation length? (2026)
- USDA-ARS Meat Animal Research Center, Germplasm Evaluation Program, Table 3 (sire breed means)
- Mississippi State University Extension P2616: The Estrous Cycle of Cattle
- Nebraska Extension: Pregnancy diagnosis in heifers and cows provides management options (2024)
Last reviewed 2026-10-21. Planning tool only. Confirm pregnancies and due dates with your veterinarian. See methodology.