Cat Pregnancy Calculator
Enter the mating date to see when kittens are due. For a queen the window is only about two days wide.
Pick a date to see the due-date window.
Not veterinary advice. The window comes from a veterinary reference. Have your vet confirm the pregnancy and talk through the birth, and use the calorie calculator only as a starting point for a pregnant or nursing queen. Read the full disclaimer.
Notes on the dates
A queen is an induced ovulator: she releases eggs because of mating, which is why one date works. Merck says the birth is 64 to 66 days from the hormone surge that mating triggers. It also says that predicting gestation length without knowing when ovulation happened is hard in dogs; for cats the mating date stands in for it, and if you do not know the mating date, a vet can estimate the age of the pregnancy from an ultrasound.
Frequently asked questions
How long is a cat pregnant?
The Merck Veterinary Manual says a queen gives birth 64 to 66 days after the luteinizing hormone surge that mating triggers. In cats, mating itself triggers ovulation, so the mating date is the date to enter.
When does the embryo implant?
Merck gives implantation at about 14 days in the queen, against about 18 days in the bitch.
How can a vet confirm it?
By ultrasound, which Merck says is the most useful method for pregnancy determination, and by X-ray later on. Ask your vet when to book.
What if the date passes?
Call your vet. The window is a normal range, not a deadline you can wait out.
Should I spay a pregnant cat or let her have the litter?
That is a decision for you and your vet, with the cat's health and the homes available for kittens in mind. PuppySizer cannot advise on it.
Sources
- Whelping and Queening in Bitches and Queens. Merck Veterinary Manual. Read 2026-11-08. Used for: Bitch: 56 to 58 days from the first day of diestrus, 64 to 66 days from the LH surge or progesterone rise, 58 to 72 days from the first accepted mating. Queen: 64 to 66 days from the LH surge triggered by mating.
- Pregnancy Determination in Bitches and Queens. Merck Veterinary Manual. Read 2026-11-08. Used for: Implantation at about 18 days (bitch) and 14 days (queen); relaxin test after 22 to 27 days; ultrasound best at 25 to 35 days; skeleton visible on X-ray from about day 42 to 45, and X-ray after 55 days is best for litter size.
Facts last checked against their sources on November 8, 2026. Read how the numbers are built on the sources and method page.