PetSums

Calving calculator

Enter the service or AI date and pick the breed to see when the calf is due.

Enter the service date and the calving date appears here.

How long cows are pregnant

The average gestation in cattle is 283 days. Breed makes a real difference, so the calculator lets you pick one. These figures come from ICBF, which records gestation lengths from Irish herd data.

Average gestation by breed
BreedAverage gestation
Cattle average283 days
Holstein Friesian279 days
Aberdeen Angus283 days
Blonde d'Aquitaine294 days

How this is calculated

Calving date = service date + gestation length in days. The result is an average, so individual cows will calve before or after it. Have everything ready a couple of weeks early and keep watching her after the date passes.

Worked example

A suckler cow was served by an Aberdeen Angus bull on 1 July 2026. At 283 days, she is due on 10 April 2027. Had the bull been a Blonde d'Aquitaine (294 days), the date would be 21 April 2027.

After the calf arrives

Calves need ear tags and a birth registration within the deadlines set by your nation's cattle tracing system. The systems and deadlines differ in England, Wales, Scotland and Northern Ireland, so check them before calving starts. If a cow has been calving for a long time without progress, or you can't correct a malpresentation, call your vet.

Questions people ask

How long is a cow pregnant?

About 283 days on average, roughly nine and a half months. ICBF data shows it varies by breed, from about 279 days for Holstein Friesians to 294 days for Blonde d'Aquitaine.

Which breed has the longest gestation?

Of the breeds listed here, Blonde d'Aquitaine at about 294 days, according to ICBF. That is roughly two weeks longer than a Holstein Friesian, so using the wrong figure can put your calving date out by a fortnight.

What if my breed is not listed?

Choose "Enter my own" and type the gestation length your breed society, AI company or vet gives for the sire. Some AI catalogues list a gestation figure for each bull.

Should I count from the first service or the last?

Count from the service that held. If she was served more than once, work out a date for each and watch her from the earliest.

Sources

  1. ICBF: Gestation length in cattle

Figures checked on 25 October 2026. Read how we calculate for the rounding and assumptions behind every tool.