# Dog Pregnancy Calculator

A dog's due date, counted from the mating date. The Merck Veterinary Manual gives about 63 days, with a window of 58–72 days when the mating is dated without ovulation testing. Past 70 days from a dated mating, the pregnancy is prolonged and warrants a call.

## Common questions

### How long is a dog pregnant?

About 63 days from mating. The Merck Veterinary Manual gives a window of 58 to 72 days when the mating date is known but ovulation wasn’t tracked.

### Why is the window two weeks wide?

Because mating and conception aren’t the same day. Sperm can wait for the egg, and eggs need time to mature. Measured from ovulation instead, the range tightens to 62–64 days — but that requires progesterone testing at the vet.

### What if she goes past the due date?

Past 70 days from a dated mating, the Merck Veterinary Manual considers the pregnancy prolonged — a separate clinical threshold from the window above, from Merck’s article on difficult labor rather than the gestation-length table. Call your veterinarian — this is one to check rather than wait out.

### Does litter size change the due date?

Yes, slightly: a Theriogenology study found bitches whelping four pups or fewer had gestations that ran about 1 day longer on average than those with five or more. The published window above already absorbs that variation.

## Sources

- Wikidata — dog breed mass (property P2067) — Wikimedia Foundation, query run 2026-07-22, CC0 license (https://query.wikidata.org/)
- Wikidata — cat breed mass (property P2067) — Wikimedia Foundation, query run 2026-07-28, CC0 license (https://query.wikidata.org/)
- 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)
- Body-Weight Changes during Growth in Puppies of Different Breeds — Hawthorne et al., Journal of Nutrition, 2004, vol. 134, p. 2027S (https://doi.org/10.1093/jn/134.8.2027S)
- Management of Reproduction — gestation period in the bitch — Merck Veterinary Manual, “Approximate Gestation Periods” table, accessed 2026-07-23 (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)
- 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://caninecalculators.com/sources

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