Cat Pregnancy Calculator: Kitten Due Date

By Marcos Ortega · Updated October 25, 2026 · Runs in your browser; nothing you type is sent anywhere.

Educational estimate, not veterinary advice. These numbers come from published averages and can be wrong for your pet. Your veterinarian, who can examine your dog or cat, is the right person to decide what is healthy for them.

Cats ovulate in response to mating, so the mating date is a good anchor for estimating when kittens will arrive. The calculator shows two windows: the usual one from the Merck Veterinary Manual, and the full range seen in a published survey.

How the calculator counts

Window	Days after mating	Source
Usual window	64–66 days	Merck Veterinary Manual: birth occurs 64–66 days from the LH surge triggered by copulation
Full range observed	57–72 days (mean 65.3)	Musters et al., Theriogenology, 2011: questionnaire survey of 197 queens

The single date the calculator highlights is the middle of the usual window (65 days), which also matches the survey’s average of 65.3 days.

Usual window = mating date + 64 … + 66 days
Full range = mating date + 57 … + 72 days

Because the LH surge follows mating closely, the calculator treats the mating date and the surge as the same day. If mating happened over several days, the true window is a little wider.

Worked examples

Example 1: mating on February 1, 2027. Usual window: Tue, Apr 6, 2027 – Thu, Apr 8, 2027. Middle (65 days): Wed, Apr 7, 2027. Full observed range: Tue, Mar 30, 2027 – Wed, Apr 14, 2027.

Example 2: matings on February 1 and February 4, 2027. Run the calculator for each date. Earliest usual start: Apr 6. Latest usual end: Feb 4 + 66 days = Apr 11. Plan for the whole of April 6–11, and keep the wider range in mind.

Getting ready

See your vet to confirm the pregnancy and talk about diet, since a pregnant and nursing queen’s needs change a lot. Our cat food calculator leaves pregnancy out for that reason.
Prepare a quiet nesting box in a warm, calm room well before the window opens.
Keep your vet’s number and the nearest emergency clinic handy. If anything worries you during labor, call.

Limitations

The usual window comes from one reference text and the full range from one survey based on owner reports; individual cats can fall outside both.
If the mating date is uncertain, so is the result.
This calculator does not confirm a pregnancy. Only a veterinarian can.

Frequently asked questions

How long are cats pregnant?

Usually about 65 days. The Merck Veterinary Manual says queens give birth 64–66 days after the LH surge triggered by mating. In a Dutch survey of 197 queens, gestation averaged 65.3 days, with a range of 57 to 72 days.

Why count from the mating date in cats?

Cats are induced ovulators: mating itself triggers the hormone surge (LH) that leads to ovulation. That makes the mating date a much better starting point in cats than in dogs.

My cat mated over several days. Which date do I use?

Use the first date for the earliest possible window, then the last date for the latest. Kittens are most likely to arrive somewhere across the two windows.

I don't know when she mated. Can I still estimate the due date?

Not with this calculator. A veterinarian can estimate how far along she is with an examination, an ultrasound or X-rays later in pregnancy.