# Cat Pregnancy Calculator

How long are cats pregnant? About 65 days from the mating date — the figure the Merck Veterinary Manual publishes for the cat. Two further 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 past 70 days from a known mating date is considered prolonged and warrants a call.

| What | Day from mating |
|---|---|
| Expected due date | 65 |
| Kittens unlikely to survive before | 61 |
| Gestation considered prolonged past | 70 |

## Why sources give different numbers

Merck's 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 days Merck does publish. Two other published sources disagree with it, and both are shown rather than smoothed over: International Cat Care puts cat pregnancy at 63–65 days, so Merck's 65 sits at the TOP of that range, not in its middle; and a study of a research colony (Root et al., Journal of the American Animal Hospital Association, 1995) measured gestations averaging 66.9 ± 2.9 days with births from 62 to 71 days — about two days longer than Merck, on 15 gestations. A veterinarian can narrow the date with ultrasound or progesterone timing, which measures the pregnancy itself instead of counting from an observed date.

## 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.

## Sources

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- Wikidata — cat breed mass (property P2067) — Wikimedia Foundation, query run 2026-07-28, CC0 license (https://query.wikidata.org/)
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- Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome — Wang et al., Cell Systems, 2020, vol. 11, no. 2, p. 176–185.e6 (DNA methylation in 104 Labradors) (https://doi.org/10.1016/j.cels.2020.06.006)
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- Obesity in Cats — overweight threshold and why ideal weight varies — International Cat Care, updated 26 September 2025 (https://icatcare.org/articles/obesity-in-cats)
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- Growth standard charts for monitoring bodyweight in dogs of different sizes — Salt et al., PLoS ONE, 2017, vol. 12, no. 9, e0182064 (correction 2024: data availability only) (https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182064)
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- Approximate Gestation Periods — gestation length in the bitch and the queen — Merck Veterinary Manual, “Approximate Gestation Periods” table, accessed 2026-07-30 (https://www.merckvetmanual.com/multimedia/table/approximate-gestation-periods)
- Dystocia in Small Animals — Merck Veterinary Manual, “Diagnosis of Dystocia in Small Animals” section, accessed 2026-07-28 (https://www.merckvetmanual.com/reproductive-system/reproductive-diseases-of-the-female-small-animal/dystocia-in-small-animals)
- Factors affecting gestation duration in the bitch — Eilts et al., Theriogenology, 2005, vol. 64, no. 2, p. 242–251 (https://pubmed.ncbi.nlm.nih.gov/15955350/)
- Nutritional Requirements of Small Animals — energy requirements of the dog and cat — Merck Veterinary Manual, “Energy” section, accessed 2026-07-23 (https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals)
- Chocolate Toxicosis in Animals — Merck Veterinary Manual, “Methylxanthine Content of Various Types of Chocolate” table and “Etiology” section, accessed 2026-07-28 (https://www.merckvetmanual.com/toxicology/food-hazards/chocolate-toxicosis-in-animals)
- ASPCA Poison Control — ASPCA, 24-hour emergency line, accessed 2026-07-28 (https://www.aspca.org/pet-care/aspca-poison-control)
- Cat pregnancy — how long pregnancy lasts in cats — International Cat Care, accessed 2026-07-30 (golden-test source, not used to build the calculation) (https://icatcare.org/articles/cat-pregnancy)
- 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) (https://pubmed.ncbi.nlm.nih.gov/8542362/)
- How old is your cat? — life stage and human equivalent age — International Cat Care (Cat Friendly Clinic), accessed 2026-07-28 (https://icatcare.org/resources/cat-friendly-clinic/how-old-is-your-cat-handout.pdf)
- The Special Needs of the Senior Cat — cat age in human years — Cornell Feline Health Center, Cornell University, accessed 2026-07-28 (golden-test source, not used to build the calculation) (https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/special-needs-senior-cat)
- Calorie Needs for an Average Healthy Adult Cat in Ideal Body Condition — WSAVA Global Nutrition Committee, updated July 2020 (golden-test source, not used to build the calculation) (https://wsava.org/wp-content/uploads/2020/07/Calorie-Needs-for-Healthy-Adult-Cats-updated-July-2020.pdf)
- Assessment of body weight for age determination in kittens — DiGangi et al., Journal of Feline Medicine and Surgery, 2019 (tables 1 and 2, weight-for-age, male and female) (https://doi.org/10.1177/1098612X19844846)
- Kitten Age & Weight Chart — ASPCA Pro, 2023 (golden-test source, not used to build the calculation) (https://www.aspcapro.org/sites/default/files/2023-08/aspca_kittenchart_2023.pdf)

Full method: https://petmeasure.com/sources

_Verified 2026-07-28. Estimates only — this does not replace veterinary advice._