Cat Pregnancy Calculator
A cat is pregnant for about 65 days — roughly nine weeks — counted from the mating date. That figure is the one the Merck Veterinary Manual publishes for the cat.
Estimated due date
September 30, 2026
Kittens born before September 26, 2026 (day 61) are unlikely to survive. Nothing by October 5, 2026 (day 70) counts as a prolonged gestation.
How long are cats pregnant?
The Merck Veterinary Manual’s table of gestation periods gives the cat 65 days. Two other clinical days come from Merck’s article on difficult labor: kittens must be born at least 61 days from breeding to be likely to survive, and a gestation running past 70 days from a known mating date is considered prolonged.
Why sources give different numbers
International Cat Care puts cat pregnancy at 63–65 days, so Merck’s 65 sits at the top of that range rather than in the middle of it. A study of a research colony (Root et al., 1995) measured something longer again: gestations averaging 66.9 days, give or take 2.9, with births falling between 62 and 71 days. That was 15 gestations — a small sample, and the reason we show it beside Merck’s figure rather than in place of it.
One more difference worth knowing: Merck’s table gives the dog a footnote with a range of days, and gives the cat a single number with no range at all. Rather than invent the missing window, this page shows the days Merck does publish and names what each one means. A veterinarian can narrow the date with an ultrasound or progesterone timing — that measures the pregnancy itself, instead of counting from a date you observed.
Common questions
How long are cats pregnant?
About 65 days from mating. That is the figure the Merck Veterinary Manual publishes for the cat. International Cat Care puts pregnancy at 63–65 days, so Merck's number sits at the top of that range rather than in the middle of it.
Why is there no due-date window like the dog calculator has?
Because Merck doesn't publish one for cats. The same table gives the dog a footnote with a 58–72 day range and gives the cat a single number, 65, with no range at all. Rather than invent the missing window, this page shows the two clinical days that Merck does publish, and names what each one means.
How early is too early for kittens to be born?
The Merck Veterinary Manual states that kittens must be born at least 61 days from breeding to be likely to survive. A birth before that day is an emergency, not an early arrival — call your veterinarian.
What if she goes past the due date?
Past 70 days from a known mating date, the Merck Veterinary Manual considers the gestation prolonged. That is a reason to call your veterinarian rather than to keep waiting.
Do other sources give the same answer?
No, and the gap is worth knowing. A study of a research colony (Root et al., Journal of the American Animal Hospital Association, 1995) measured gestations averaging 66.9 days — about two days longer than Merck's figure — with births ranging from 62 to 71 days. That was 15 gestations, so it is a small sample; we show it because it is the only published range we found, not because it settles the question.
Can a vet give a more exact date?
Yes. Ultrasound and progesterone timing measure where a pregnancy actually is, instead of counting from a mating date that may not be the day of conception. Any calculator, including this one, is counting days from something you observed — a veterinarian can measure the pregnancy itself.
This is an estimate counted from the mating date, not a measurement of the pregnancy. Actual timing varies, and it does not replace a veterinarian’s exam. Call your veterinarian if kittens arrive before day 61, or if nothing has happened by day 70.
Verified on . Based on Approximate Gestation Periods — gestation length in the bitch and the queen (Merck Veterinary Manual, “Approximate Gestation Periods” table, accessed 2026-07-30), Dystocia in Small Animals (Merck Veterinary Manual, “Diagnosis of Dystocia in Small Animals” section, accessed 2026-07-28), Cat pregnancy — how long pregnancy lasts in cats (International Cat Care, accessed 2026-07-30 (golden-test source, not used to build the calculation)) and Estrous length, pregnancy rate, gestation and parturition lengths, litter size, and juvenile mortality in the domestic cat (Root et al., Journal of the American Animal Hospital Association, 1995, vol. 31, no. 5, p. 429–433 (golden-test source, not used to build the calculation)). See the method.