Gestation length varies enormously across species — a rabbit is ready to give birth in about a month, while a mare can carry a foal for nearly a year. This calculator applies the average gestation length for eight common species to a breeding date, so pet owners, farmers, and breeders can plan ahead with a realistic due date and window.
How the Animal Gestation Calculator works
The calculator adds a species' average gestation length, in days, to the breeding date to produce an estimated due date. Gestation lengths used here follow standard veterinary references: dogs and cats average 63 days, cows 283 days, horses 340 days, goats 150 days, sheep 147 days, pigs 114 days, and rabbits 31 days. Because no two pregnancies run exactly the same length, the calculator also applies each species' typical minimum-to-maximum range to show an early and late due date, not just a single point estimate.
Inputs and what they mean
Species selects which gestation length and window apply. Breeding date is the date mating occurred — the more precisely this is known, the more accurate the due date estimate will be. Horses have an unusually wide normal range (320–370 days) compared to dogs and cats, so a horse breeder should expect more uncertainty in the estimate than a dog owner would.
Limits and edge cases
This calculator gives a species-average estimate, not an individualized medical prediction — factors like breed, litter size, and the individual animal's health can shift the actual delivery date within or even slightly outside the typical window. It should not replace guidance from a veterinarian, especially as the estimated due date approaches or if any signs of complication appear. The breeding date itself is also an estimate for animals bred over multiple days or through natural pasture breeding, which adds further uncertainty to the result.