Cow Gestation Period: How Long Is a Cow Pregnant?

How long is a cow pregnant?

A cow carries her calf for an average of 283 days, or about 9 months and 1 week. Counting from the breeding date, calving is normal anywhere from day 279 to day 292.

Key checkpoints across the 283-day cow gestation, measured in days from breeding:

Estimate your cow's calving date

Enter the breeding date for an estimated calving date at 283 days.

Open the full Cow gestation calculator

Cow gestation stages, month by month

Signs a cow is pregnant

• No return to oestrus roughly 21 days after service
• Positive rectal palpation from about day 35 or ultrasound from day 28
• Blood or milk pregnancy-associated glycoprotein test positive from about day 28
• Gradual abdominal enlargement on the right side from mid gestation

Signs of approaching calving

• Udder development in the last four to six weeks, earlier in heifers
• Relaxed pelvic ligaments, a slack tailhead and a swollen vulva in the final days
• Contact your vet if labour stalls, if the animal strains without progress, or if there is abnormal discharge before calving begins.

What affects cow gestation length

• Gestation length is moderately heritable and is influenced more by the sire's breed than by the dam's, because the calf's own genetics affect when labour begins.
• Bull calves are carried on average one to two days longer than heifer calves.
• Twins shorten gestation by roughly five to ten days and raise the risk of retained placenta and freemartin heifers.
• Cows carrying a calf through a hot summer often calve slightly earlier, while cold conditions late in gestation tend to lengthen gestation by a few days.

Cow gestation chart

Every fifth breeding date across the year with the matching calving date, calculated at 283 days. Find the row closest to the date the cow was served; because normal gestation spans 279 to 292 days, plan for a window of a few days either side. Filter by month, or print the chart for the barn wall or breeding record: navigation, buttons and adverts are hidden on paper.

Cow gestation length by breed

Sources for cow gestation figures

Figures on this page are drawn from Beef Improvement Federation standards, and checked against the references below. Averages describe healthy animals under normal management; individual animals vary, and nothing here replaces advice from your vet.

• Beef Improvement Federation — breed gestation standards
• Merck Veterinary Manual — reproduction and pregnancy chapters by species
• Penn State Extension — livestock reproduction and breeding management fact sheets
• Oklahoma State University, Breeds of Livestock