Animal Gestation Due Date Calculator
Planning for the birth of animals requires knowing when to expect parturition. The expected due date is calculated by adding the species-average gestation period in days to the date of breeding or confirmed mating. This calculator covers common species: dogs (63 days), cats (63 days), horses (340 days), cattle (280 days), goats (150 days), sheep (147 days), pigs (114 days), and rabbits (31 days). These average values are from USDA and NRC reference data. Because individual variation is normal, treat the calculated date as the center of a window rather than an exact date, and begin close monitoring one to two weeks before the due date.
Gestation due date formula
Due date = Breeding date + Average gestation period (days)
Average gestation values used (USDA reference): Dog 63 days, Cat 63 days, Horse 340 days, Cattle 280 days, Goat 150 days, Sheep 147 days, Pig 114 days, Rabbit 31 days. Actual delivery may occur several days before or after the calculated date.
Gestation reference periods by species
- Dog: 58-68 days (average 63), count from ovulation for most accuracy.
- Cat: 60-69 days (average 63-65).
- Horse: 320-370 days (average 340); mares foal in spring due to seasonal light cues.
- Cattle: 275-295 days (average 280); varies with breed and sire breed.
- Goat: 145-155 days (average 150).
- Sheep: 144-152 days (average 147); varies by breed.
- Pig: 112-116 days; commonly remembered as 3 months, 3 weeks, 3 days.
- Rabbit: 29-35 days (average 31).
Animal gestation calculator: frequently asked questions
What is the gestation period for dogs?
The average gestation period for domestic dogs is 63 days (range 58-68 days) from the day of ovulation. From the first breeding date, whelping typically occurs between 58 and 68 days. Accurate due dates require progesterone testing or vaginal cytology to pinpoint ovulation.
What is the gestation period for cats?
Cats have an average gestation of approximately 63-65 days from mating, with a normal range of 60-69 days. Queens can deliver healthy litters from day 58 onward. Kittens born before day 57 are generally not viable.
What is the gestation period for horses?
Mares carry foals for approximately 335-342 days (about 11 months), with a normal range of 320-370 days. Gestation length varies with season (longer in winter), breed (draft horses tend to carry longer), and individual variation.
What is the gestation period for cattle?
Beef and dairy cows have an average gestation of approximately 280 days (9 months), with a range of 275-295 days. The specific breed affects length slightly; for example, Brahman crosses tend to have longer gestations than British breeds.
How accurate is a due date calculated from breeding date?
The calculated due date is an estimate based on average species gestation. Individual variation is common. For livestock production planning, use the expected date as a window of plus or minus one to two weeks depending on the species. Close monitoring in the final weeks is recommended.
Official sources
- USDA Animal and Plant Health Inspection Service: APHIS Homepage.
- USDA National Agricultural Library: Animal Health and Welfare.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.