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Cat Pregnancy Calculator
Use this free cat pregnancy calculator to work out when your cat's kittens are due. Enter the mating date — or the date you think conception happened — and the calculator adds the usual 63 to 65 days of gestation to give an expected due date, a due-date window, and a week-by-week guide to what is happening inside and what you should do at each stage. It also counts the days remaining, so you know exactly how much time you have to prepare a nesting box and book a vet check.
If you are not sure of the exact mating date, use the first day you saw mating, or the middle of the mating period. Cats can mate more than once over a few days, so the due date is a window, not a single fixed day.
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How the cat pregnancy calculation works
A cat's pregnancy lasts about 9 weeks. The standard figure vets use is 63 to 65 days from mating to birth, with 63 days the most commonly quoted single number. Some healthy pregnancies are a little shorter or longer — roughly 61 to 70 days — which is why this calculator shows a due-date window rather than pretending the day is certain. If your cat mated over several days, count from the first mating day and expect birth within a few days of the calculated date.
The calculation itself is simple addition: due date = mating date + 63 days. For example, mating on November 7, 2026 gives January 9, 2027 (63 days later), with the window running to January 11, 2027 at 65 days. The calculator also works out how far along the pregnancy is on any date you choose, so you can check today and see which week your cat is in and what to expect next.
Due window = mating date + 63 days to mating date + 65 days
What happens inside follows a steady pattern. In weeks 1 to 2 the fertilized eggs travel to the uterus and implant; there are usually no visible signs, and the cat behaves normally. In week 3 the nipples become pink and enlarged — the classic early sign breeders call "pinking up" — and some cats have a short spell of morning sickness, eating less for a few days. Weeks 4 to 5 bring a growing belly and a rising appetite, and an ultrasound can confirm the pregnancy from about day 16, with heartbeats visible from around day 21.
By week 6 the kittens are growing fast and the mother's belly is clearly round. Her food intake should rise, and this is the point to switch to a high-quality kitten food, which has more calories, protein, and calcium than adult food. Around day 42 an X-ray can count the kittens, which helps you know when labor is finished. In week 7 you can often feel the kittens moving if you rest a hand gently on her belly, and her nipples start to produce milk. Week 8 is preparation time: she will sleep more, eat smaller meals more often because the kittens press on her stomach, and start looking for a quiet nesting spot.
Week 9 is birth week. In the last day or two before labor, many cats go off food, become restless, groom themselves a lot, and settle into the nest. Labor itself usually lasts 2 to 6 hours for the whole litter, with kittens arriving 10 to 60 minutes apart. First-time mothers and very small or very large litters can take longer. The average litter is 3 to 5 kittens, though first litters are often smaller and some cats have 7 or more.
Knowing the due date matters because it tells you when to act. Book a vet visit in the first 3 weeks to confirm the pregnancy and check health and vaccinations. Set up the nesting box about a week before the due date, in a warm, quiet, draft-free spot, and keep the vet's emergency number handy for the birth. Call the vet without delay if there is bleeding, heavy discharge, vomiting that will not stop, or strong straining for more than 20 to 30 minutes with no kitten, or if more than 2 hours pass between kittens.
Worked example
Your cat mated on November 7, 2026. When are the kittens due?
Step 1: Start from the mating date — November 7, 2026.
Step 2: Add 63 days — November has 23 days left after the 7th, December adds 31, and 9 days into January reaches 63. That is Saturday, January 9, 2027.
Step 3: Add 65 days for the end of the window — Monday, January 11, 2027.
Step 4: Milestones — nipples turn pink around November 28, the belly starts to show around December 12, and the nesting box should be ready by January 2.
So the kittens are due around January 9, 2027, within the window of January 9–11, 2027. Enter your own cat's mating date above to get her dates.
FAQ
How long is a cat pregnant for?
A cat's pregnancy, or gestation, usually lasts 63 to 65 days from mating, which is about 9 weeks. Some healthy pregnancies run a few days shorter or longer, roughly 61 to 70 days, so the due date is best thought of as a window rather than a single day. This calculator shows the expected due date at 63 days plus the full 63–65 day window.
How can I tell if my cat is pregnant?
The earliest sign is usually pink, enlarged nipples around 2 to 3 weeks after mating, sometimes called pinking up. Later signs include a growing belly from about week 5, increased appetite, more sleep, and seeking quiet hiding spots near the end. The only certain confirmation is a vet visit: an ultrasound can confirm pregnancy from about day 16, and X-rays can count kittens from about day 42.
When should I take my pregnant cat to the vet?
Book a vet visit as soon as you suspect pregnancy, ideally in the first 3 weeks. The vet can confirm the pregnancy, check the cat's health and vaccinations, advise on food, and estimate the litter size later in pregnancy. Call the vet urgently if there is bleeding, heavy discharge, vomiting that does not stop, or straining for more than 20 to 30 minutes without a kitten.
What should I feed a pregnant cat?
Feed a complete, high-quality kitten food from the second half of pregnancy onward, because it has more calories, protein, and calcium than adult food. Increase the amount gradually, since a pregnant cat needs roughly 25 to 50 percent more calories in the last weeks, and keep fresh water available at all times. Do not add calcium supplements unless your vet tells you to, as too much calcium can cause problems.
How do I prepare a nesting box for my cat?
Set up a quiet, warm, draft-free box in a low-traffic spot about a week before the due date. Use a sturdy cardboard box with a low entry side, lined with clean towels or blankets you can change. Show it to your cat but let her choose: many cats pick their own spot, so having two or three options helps. Keep children and other pets away from the nesting area.