Animal Gestation Calculator
Find the due date for a pregnant pet or farm animal from the mating date, with the normal birth window and how many days to go. Advanced adds two mating dates, dog hormone tests, due date back to mating date and a calendar file.
Opens in Google Calendar, Apple Calendar or Outlook. The file is made in your browser.
When to call the vet
These are common rules of thumb, not a diagnosis. If you’re worried, call your vet; it’s always fine to ask.
Also handy: how much to feed her (pregnant and nursing pets need more) and the dog & cat age calculator.
How your due date is worked out
Your numbers, step by step, from typical pregnancy lengths.
- 1
Start on day 0
Mating
1 Oct 2026 - 2
Add 63 days
+ 63 days =
3 Dec 2026 - 3
Normal range
57 to 72 days
27 Nov – 12 Dec - 4
Where you are
Day 10 of 63
53 days to go
Read more: the formula, a worked example and every animal’s pregnancy length
Each kind of animal has a typical pregnancy length, counted from the day she was mated. Add it to the mating date for the most likely due date, and add the shortest and longest normal lengths for the window when birth is normal. Real births spread around the typical day, so treat the due date as the middle of a window, not an appointment.
The formula
due date = mating date + typical length
earliest = first mating + shortest normal length
latest = last mating + longest normal length
days to go = due date − today
progress = days since mating ÷ typical length
back from a due date: mating date = due date − typical length
For dogs counted from a hormone test, the typical length changes: 65 days from the LH surge (64 to 66), 63 days from ovulation (62 to 64) or 57 days from the first day of diestrus (56 to 58). The milestones are still counted from the mating day those dates point to.
Worked example
A dog (the default) mated on 1 October 2026: 30 days to 31 October, 30 more to 30 November, then 3 more, so 1 October + 63 days = Thursday 3 December 2026. The normal window is 1 October + 57 days = 27 November to 1 October + 72 days = 12 December 2026. On 11 October she is on day 10 (week 2), with 63 − 10 = 53 days to go, and 10 ÷ 63 = 16% of the way. If she was mated again on 3 October, the window runs to 3 October + 72 = 14 December.
Typical pregnancy lengths
| Animal | Typical | Normal range | About |
|---|---|---|---|
| Dog | 63 days | 58–72 days | 9 weeks |
| Cat | 65 days | 60–70 days | 9.3 weeks |
| Rabbit | 31 days | 29–35 days | 4.4 weeks |
| Guinea pig | 66 days | 59–72 days | 9.4 weeks |
| Hamster (Syrian) | 16 days | 15–18 days | 2.3 weeks |
| Hamster (dwarf) | 20 days | 18–22 days | 2.9 weeks |
| Ferret | 42 days | 41–43 days | 6 weeks |
| Rat | 22 days | 21–23 days | 3.1 weeks |
| Mouse | 20 days | 19–21 days | 2.9 weeks |
| Horse | 340 days | 320–370 days | 11.2 months |
| Donkey | 365 days | 340–395 days | 12 months |
| Cow | 283 days | 279–290 days | 9.3 months |
| Goat | 150 days | 145–155 days | 4.9 months |
| Sheep | 150 days | 144–155 days | 4.9 months |
| Pig | 114 days | 111–117 days | 16.3 weeks |
| Alpaca | 345 days | 335–360 days | 11.3 months |
| Llama | 350 days | 335–360 days | 11.5 months |
| Camel (dromedary) | 390 days | 365–400 days | 12.8 months |
Lengths are counted from mating. Breed, age, litter size, season and the animal’s condition all move them a little: big litters often come a bit early and single babies a bit late. Sources: Merck Veterinary Manual, approximate gestation periods; dogs and cats: Merck, whelping and queening and breeding management of dogs and cats.
Why a dog’s due date from mating is so uncertain
A dog’s eggs need about two days to mature after ovulation, and sperm can live in her for several days, so a mating can happen well before or after the fertile days. That’s why the normal range from mating is 57 to 72 days. Vets who time a breeding with blood tests (progesterone and the LH surge) can predict the day within about one day either side.
Week by week (typical)
The milestones shown for dogs and cats are typical timings, counted from mating. For horses and cows the calculator shows the usual first pregnancy check, the last third (when the baby grows fastest) and a get-ready date. For other animals it shows the thirds and a get-ready date before the window opens.
For information only. Please check dates, feeding and care with your vet.
Common questions
How long is a dog pregnant?
About 63 days (9 weeks) from mating, with a normal range of 58 to 72 days. The range is wide because sperm can live for several days and eggs need time to mature after ovulation. Counted from the LH surge found by a blood test, it is much tighter: 65 days, give or take a day.
How long is a cat pregnant?
About 65 days, or just over 9 weeks, from mating, with a normal range of about 60 to 70 days. Her nipples usually turn pink and get bigger (called “pinking up”) about 15 to 21 days in, and a vet can often confirm the pregnancy by ultrasound from about 21 to 25 days.
How do I work out my animal’s due date?
Add the typical pregnancy length to the mating date. For a dog that is 63 days, for a goat 150 days and for a cow 283 days. Then add the earliest and latest normal lengths to get a birth window. If she was mated more than once, the window runs to the last mating plus the longest length.
How long is a horse pregnant?
A mare is usually pregnant for about 340 days, or around 11 months, and anywhere from 320 to 370 days is normal. Donkeys carry for longer, about 365 days (340 to 395). Mares often go a little longer when they foal in early spring than in summer.
How long are cows, goats, sheep and pigs pregnant?
Typical lengths are about 283 days for a cow (279 to 290), 150 days for a goat (145 to 155), 150 days for a sheep (144 to 155) and 114 days for a pig (111 to 117). The pig figure is the old “3 months, 3 weeks and 3 days” rule.
When should I call the vet?
Call your vet if she goes past the end of the normal window, strains hard for 30 minutes with nothing born, goes more than 2 hours between babies, has green or dark discharge before the first birth, bleeds heavily or seems unwell. For dogs, call if there are no puppies by about day 70 from the first mating.
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