Free breeder tool
Gestation due date calculator
Enter the mating date to get the due date, a likely birth window and the milestones to put on your calendar. Works for cats, dogs, rabbits, horses, goats and sheep.
Estimated due date (64 days)
Tue, Dec 15, 2026
Most likely between Dec 13 and Thu, Dec 17, 2026. Normal range for a cat: 63–65 days after mating.
Milestones
- Oct 27 – Nov 2 day 15–21Pinking upNipples become pinker and more prominent.
- Oct 28 – Nov 2 day 16–21Earliest ultrasoundA vet can usually confirm the pregnancy by ultrasound from about day 16; day 21 is reliable.
- Oct 29 – Nov 6 day 17–25Abdominal palpationKittens can be felt as small, evenly spaced swellings. Leave this to your vet.
- Nov 23 – Dec 1 day 42–50X-ray kitten countSkeletons show on X-ray from about day 42; later films give a more accurate count.
- Dec 6 day 55Set up the queening boxMost queens start nesting in the last week or so.
- Dec 14 day 63Temperature drop (if any)Some queens drop below about 100°F / 37.8°C roughly 12–24 hours before labour. Less reliable than in dogs.
- Dec 15 day 64Kittening due
How gestation length is worked out
The calculator adds a typical gestation length to the mating date. For cats that is 63 to 65 days (we use 64), for dogs 63 days, rabbits 31, goats about 150, sheep about 147 and horses about 340. Because nobody knows the exact moment of conception, the result is a window: we show two days either side of the estimate, and the normal range for each species is wider still. Cats are induced ovulators, so the first mating is a good anchor. Dogs are different: a bitch can conceive days after she is bred, which is why dog due dates are most accurate when counted from the progesterone-confirmed ovulation date.
Using the milestones
The milestone list turns a single date into a plan. Book the confirmation ultrasound early (around day 21 for queens, 25 to 28 for bitches), schedule an X-ray late in the pregnancy if you want a count so you know when labour is finished, and have the nesting box ready a week or so ahead. For dogs, start taking her temperature twice a day from about day 56. A drop of a degree or more below her baseline usually means puppies within a day. Queens do not show that drop as reliably, so watch for nesting, restlessness and loss of appetite instead.
When to call the vet
Gestation ranges are guidelines, not guarantees. Call your vet if she is past the end of the normal range, has strong straining for 30 minutes or more without producing a baby, shows green or bloody discharge before the first birth, or seems unwell at any point. This tool is for planning and does not replace veterinary care.
Track every pregnancy automatically
In BreederPro you log the mating once and the estimated due date shows on it automatically, based on the gestation length you set for that breeding program. Add reminders for the ultrasound or X-ray, and on the Pro plan subscribe to them from your phone’s calendar. When the babies arrive, record the litter against the mating and BreederPro shows the real gestation for that pairing, so over time you learn your own lines’ timing instead of relying on textbook averages.
Frequently asked questions
How long are cats pregnant?
Most queens deliver 63 to 65 days after mating, and anywhere from about 58 to 70 days can be normal. Count from the first mating if she was bred over several days.
How long are dogs pregnant?
About 63 days from ovulation. Counted from the mating date, whelping usually falls between 58 and 68 days because sperm can survive for several days before ovulation. Progesterone timing narrows the window.
Why does the calculator show a range and not just one day?
Gestation varies with litter size, breed and the individual animal, and the true conception date is rarely known exactly. Plan to be ready for the whole window, and call your vet if she goes well past it.
Should I count from the first or the last mating?
Use the first mating for planning. It gives the earliest likely date, so you are prepared in time. If you know the ovulation date from progesterone testing, enter that instead and set the gestation to 63 days for dogs.
Can I use a different gestation length for my breed?
Yes. Enter your own number in the gestation override box. Many breeders use their own lines’ history. BreederPro shows the actual gestation of every recorded litter, and each breeding program can have its own default.
Last reviewed October 8, 2026. For information only. Not veterinary advice.
Let BreederPro do this for you
Log a mating in BreederPro and the estimated due date appears on it automatically, using the gestation length you set for that breeding program. When the litter arrives you record it against the mating, track weights from day one and see each pairing’s real gestation. Free to start, no card needed.