Enter a cow's breeding date for the calving due date — or reverse it and enter the calf's birth date to find the breeding window.
A cow's gestation averages about 283 days — roughly 9 months and 10 days. Most calves arrive between 279 and 287 days, with a broader normal range of about 273 to 296 days depending on breed and calf sex (bull calves are often carried slightly longer). This calculator adds 283 days to the breeding date for the expected calving date.
Already have a calf on the ground? Switch to reverse mode and enter the birth date. The calculator subtracts about 283 days to estimate the breeding date and shows a breeding window — useful for confirming the service date and working out which bull was the likely sire.
Gestation varies by breed and individual, so treat this as a general estimate for herd planning, not veterinary advice. Source: average bovine gestation of ~283 days (about 273–296 day range) as used by breed associations and livestock extension references.