Sheep Gestation Calculator by MarkSheep Gestation CalculatorEstimate your ewe’s lambing date and track pregnancy stages. Breeding Date ? Select the date of successful breeding (e.g., 2025-04-01). Gestation Period (days) ? Average is 147 days; range is 144–152 days (e.g., Merino: ~150, Suffolk: ~145). Calculate ResetEnter the breeding date, then click “Calculate”. JavaScript is disabled. Please enable it to use the calculator.