How cat due dates are calculated
A cat's pregnancy lasts about 63 to 65 days from mating, a little over nine weeks. Normal pregnancies range from roughly 61 to 72 days, so this calculator gives a single estimated due date at day 63, a most-likely window of days 63–65 and the full normal range.
The range exists because cats are induced ovulators. A queen doesn't release eggs on a fixed schedule; mating triggers ovulation about 24 to 36 hours later, and it often takes several matings to trigger it. A cat in heat can mate repeatedly over four to seven days, sometimes with more than one tom, so the exact day of conception is rarely known. That is why you should enter the first mating date.
The formula
most likely window = mating date + 63 to 65 days
normal range = mating date + 61 to 72 days
days along = today − mating date
Example: mated on June 1, 2026
For a cat that first mated on Monday, June 1, 2026:
| Milestone | Day | Date |
|---|---|---|
| Mating | 0 | Jun 1 |
| Pinking | 15–18 | Jun 16 – Jun 19 |
| Palpation possible | 17–25 | Jun 18 – Jun 26 |
| Ultrasound window | 21–35 | Jun 22 – Jul 6 |
| X-ray shows skeletons | 45+ | From Jul 16 |
| Nesting box ready | 58–60 | Jul 29 – Jul 31 |
| Estimated due date | 63 | Mon, Aug 3, 2026 |
| Most likely window | 63–65 | Aug 3 – Aug 5 |
| Normal range | 61–72 | Aug 1 – Aug 12 |
Signs and stages week by week
Weeks 1–3 (days 0–21)
Fertilized eggs reach the uterus and implant around days 12–14. Her heat behavior stops, and some cats sleep more or eat a little less. The first visible sign is usually pinking around days 15–18, when the nipples swell and turn a deeper pink. It is easiest to spot in a first pregnancy.
Weeks 4–6 (days 22–42)
This is the best time to confirm the pregnancy. A vet can often feel the walnut-sized swellings of developing kittens by palpation up to about day 25; after that the uterus fills out and they are harder to feel individually. Ultrasound shows heartbeats from about three weeks on. Her appetite picks up and her belly starts to round.
Weeks 7–9 (days 43–63+)
From about day 45 kitten skeletons are visible on an x-ray, and a film taken after day 55 gives the most reliable count, which helps you know when she has finished delivering. In the last week she will look for a quiet, enclosed place to nest. Labor usually follows within a day of restlessness, loss of appetite and heavy grooming.
Practical tips
- Switch to kitten food. Pregnant and nursing queens need more energy, protein and calcium; a complete kitten or all-life-stages food provides it. Let her eat more as pregnancy progresses, and skip supplements unless your vet prescribes them.
- Prepare a nesting box early. A cardboard box lined with towels in a warm, quiet room, set up a week or two before the due date, gives her time to accept it.
- Keep her indoors. Late-pregnancy cats may wander off to give birth somewhere hidden.
- Know when to call. Twenty to thirty minutes of hard straining with no kitten, more than two hours between kittens, or a foul discharge all need a vet.
- Plan the next step. Cats can come back into heat within weeks of giving birth, even while nursing. Ask your vet about spaying once the kittens are weaned.
This calculator gives estimates for planning and is not veterinary advice. Have your vet confirm the pregnancy and supervise her care.
Frequently asked questions
How long are cats pregnant?
Most cats give birth 63 to 65 days after mating, about nine weeks. A normal pregnancy can be as short as about 61 days or as long as 72 days, so the due date is an estimate rather than a fixed day.
What is pinking in cats?
Pinking is when a pregnant cat's nipples become enlarged and turn a rosier pink. It usually shows around days 15 to 18 after mating and is one of the earliest signs you can see at home, especially in a cat that has not had kittens before.
When can a vet confirm my cat is pregnant?
An experienced vet can often feel the developing kittens by gently palpating the abdomen from about 17 to 25 days. Ultrasound can confirm pregnancy and heartbeats from about three weeks. X-rays show kitten skeletons from about day 45 and are the best way to count kittens late in pregnancy.
My cat mated several times. Which date should I use?
Use the first mating date. Cats are induced ovulators, so they release eggs roughly 24 to 36 hours after mating, and a queen in heat may mate many times over several days. Counting from the first date gives the earliest reasonable due date.
What are the signs a cat is about to give birth?
In the last day or two a queen often becomes restless, searches for a quiet nest, stops eating, grooms her belly and vulva a lot and may vocalize or pant. Her rectal temperature can drop below about 99°F (37.2°C) within 24 hours of labor, although this is less consistent in cats than in dogs.
When should I call the vet?
Call if she strains strongly for 20 to 30 minutes without a kitten, if more than two hours pass between kittens while she is still straining, if there is a foul or bloody discharge before the first kitten, if she seems weak or distressed, or if there is no sign of labor as she approaches 66 to 70 days.
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