How the due date window is worked out
The Merck Veterinary Manual says queening happens 64 to 66 days after the LH surge, the hormone signal that mating triggers in cats. Because cats ovulate in response to mating, the calculator counts those days from the mating date.
Likely window = first mating + 64 days to last mating + 66 days
Wider normal range = first mating + 52 days to last mating + 74 days
The wider range comes from a review of cat pregnancies (Root Kustritz, Theriogenology, 2006), which found an average of 65.6 days from mating and a range of 52 to 74 days. The average falls inside the likely window; the wider range shows what has been reported in normal pregnancies.
Worked example
A cat mated on October 1 and again on October 3, 2026. Likely window: October 1 + 64 days = December 4, to October 3 + 66 days = December 8. Wider range: October 1 + 52 days = November 22, to October 3 + 74 days = December 16.
Getting ready
- Ask your vet to confirm the pregnancy and talk through diet; pregnant and nursing cats need more food.
- Set up a quiet, warm box in a low-traffic room a week or two before the window opens.
- Save the number of the nearest 24-hour emergency clinic.
- Call your vet if she passes the end of the window, seems ill, has a green or bloody discharge before a kitten arrives, or strains without producing a kitten.
Sources checked October 2026.
Questions people ask
How long is a cat pregnant?
About 9 weeks. The Merck Veterinary Manual puts queening (giving birth) 64 to 66 days after the hormone surge that mating triggers. A review of cat pregnancies by Root Kustritz (2006) found an average of 65.6 days from mating, with a normal range of 52 to 74 days.
Why does the mating date work better for cats than for dogs?
Cats are induced ovulators: mating itself sets off the LH surge that releases the eggs. So the mating date is close to the start of the pregnancy, while in dogs ovulation and mating can be days apart.
My cat mated several times over a few days. Which date do I use?
Enter the first mating as the date and the last mating as the last date. The calculator counts the earliest date from the first mating and the latest from the last, so the window covers both.
How can I tell if my cat is pregnant?
Your vet can confirm it with an ultrasound or by feeling the belly, and an x-ray late in pregnancy can count the kittens. Home signs such as pinker, larger nipples and weight gain show up later and are not reliable on their own.
When should I call the vet?
Call if she passes the end of the window with no kittens, seems unwell, has a green or bloody discharge before any kitten is born, or strains without producing a kitten. Ask your vet in advance which signs during labor they want to hear about.