How Long Are Cows Pregnant?
About 283 days, which is a little over nine months. That is the figure most gestation charts use, but individual cows vary by a week or more, and modern beef herds may average a few days less.
What the research says
- 283 days is the traditional average, described by Oklahoma State University's Mark Johnson as the length “commonly believed” by breeders.
- A 2024 Journal of Animal Science abstract covering 10,037 AI-bred beef cows found an average of 280.2 days, with a shortest gestation of 253 days and a longest of 300.
- In that study, fall-calving cows averaged 279.1 days and spring-calving cows 281.1 days.
- Bull calves were carried slightly longer (280.8 days) than heifer calves (279.6 days).
Gestation length by breed
The USDA Meat Animal Research Center compared calves by sire breed in its Germplasm Evaluation Program. Average gestation lengths ranged from about 281 days for Holstein-sired calves to over 290 for Bos indicus breeds:
| Sire breed | Average gestation (days) |
|---|---|
| Holstein | 281.0 |
| Jersey | 282.0 |
| Shorthorn | 284.0 |
| Red Poll | 284.6 |
| Gelbvieh | 285.6 |
| Simmental | 286.4 |
| Charolais | 286.2 |
| Salers | 284.8 |
| Maine-Anjou | 284.8 |
| Brangus | 284.7 |
| Santa Gertrudis | 285.2 |
| Limousin | 288.1 |
| Piedmontese | 287.2 |
| Brahman | 290.9 |
| Nellore | 293.0 |
| Sahiwal | 293.7 |
These are sire-breed averages from crossbred matings in an older program, so treat them as a guide. A 1952 study recorded 281.7 days for Angus and 286.1 for Hereford.
How long is that in months?
283 days is 9 months and about 10 days. A cow bred on May 1 calves around February 8 the following year.
When can you tell she is pregnant?
Nebraska Extension gives ultrasound from about 28 days after breeding, blood tests from 25 days in heifers and 28 days in cows, and rectal palpation from 35 to 50 days by an experienced technician.
Plan the whole herd
The breeding season planner takes bull-in and bull-out dates or a list of AI dates and gives you the calving schedule, and the printable cattle gestation chart covers every breeding date of the year.
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. Not veterinary advice.