by MarkEnhanced Cow Gestation CalculatorEstimate your cow’s calving date and track pregnancy stages. Breeding Date ? Select the date of successful breeding (e.g., 2025-04-01). Gestation Period (days) ? Average is 283 days; range is 279–292 days (e.g., Angus: 281, Holstein: 279). Calculate ResetEnter the breeding date, then click “Calculate”. JavaScript is disabled. Please enable it to use the calculator.