Animal Gestation Calculator
Calculate the estimated due date for any livestock or pet.
Enter the conception date and select from cow, horse, sheep, pig, goat, dog, cat, and more.
Animal Gestation Calculator
Gestation is the period from conception (fertilization) to birth. Each species has a characteristic gestation length shaped by the animal’s size, metabolism, and offspring development needs.
Average gestation periods by species:
| Species | Average Gestation | Normal Range | Spread |
|---|---|---|---|
| Hamster | 16 days | 15 to 18 days | 3 days |
| Rabbit | 31 days | 28 to 35 days | 7 days |
| Cat | 63 days | 58 to 67 days | 9 days |
| Dog | 63 days | 57 to 70 days | 13 days |
| Guinea Pig | 68 days | 59 to 72 days | 13 days |
| Pig | 114 days | 110 to 120 days | 10 days |
| Sheep | 147 days | 140 to 160 days | 20 days |
| Goat | 150 days | 145 to 155 days | 10 days |
| Cow (cattle) | 283 days | 276 to 295 days | 19 days |
| Horse (mare) | 335 days | 320 to 362 days | 42 days |
| Alpaca | 345 days | 330 to 360 days | 30 days |
| Llama | 350 days | 330 to 370 days | 40 days |
| Donkey | 365 days | 350 to 380 days | 30 days |
That last column is the one worth reading. A hamster is due within a three-day window and a mare within six weeks, so the same due date means very different things depending on what you are waiting for. Treat the number this calculator gives you as the middle of the range, not a deadline.
Important notes:
- These are averages, and individual animals vary
- Breed matters: miniature horses may foal before 320 days, and large-breed dogs (Great Danes) tend toward 63 to 65 days
- Twins or multiples usually shorten gestation slightly in cattle and sheep
- Stress, nutrition, and management all move the actual birth date
Using this calculator: Enter the confirmed conception date, or the first breeding or service date if that is what you recorded. When the exact mating date is unknown, the result is still useful as a planning window. Watch closely during the last 10% of gestation, which is the point the calculator marks for you.
Veterinary note: An animal that passes the top of its normal range is genuinely overdue, and that is what the panel flags. Prolonged gestation can mean fetal distress, a malpresentation, or a stalled labour, all of which need a vet rather than more waiting. For rabbits in particular the nest box should go in at the early end of the window, around day 28, not on the due date itself.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.