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Cat gestation averages 63-67 days. A guide, not veterinary advice: have pregnancy confirmed by a vet, and note that unspayed cats can become pregnant again within weeks of giving birth.
What The Cat Pregnancy Calculator Works Out
- Expected due date: the mating date plus 65 days, the middle of the normal cat gestation. So a 1 September mating points to kittens around 5 November. Cats are induced ovulators (mating itself triggers ovulation), which makes the arithmetic unusually reliable when the date is known.
- Normal window: 63 to 67 days from mating. A queen calling repeatedly outdoors is very likely to return pregnant, sometimes by more than one tom in the same litter.
- Milestones: "pinking up" of the nipples at about three weeks, when a vet can also confirm by ultrasound; a growing appetite and belly through weeks five to seven; kitten food and a warm, quiet nesting box from week 7, before she chooses the airing cupboard herself.
- Gestation length and days with the tom (advanced): override the 65-day average if your vet has dated the pregnancy, and add the days the queen spent with the tom, which widens the late end of the window.
- Today (advanced): which day and week of the pregnancy it is now and how many days remain, or a warning if the window has passed. Straining hard for over an hour without a kitten, more than a couple of hours between kittens with more clearly to come, or significant bleeding are emergency vet calls.
- X-ray kitten count (advanced): skeletons show on X-ray from day 55, so you know how many to expect. An average litter is four.
- Kittens can leave from (advanced): the date the kittens reach your chosen leaving age. Eight weeks is the legal minimum for sale in England; welfare bodies prefer 12, and GCCF-registered pedigree breeders rehome at 13 weeks, fully vaccinated, so choosing "pedigree" sets 13 weeks as the floor.
- First vaccination and neutering dates (advanced): kittens have their first vaccination at 8 to 9 weeks, and can be neutered from 4 months, which matters because a queen can be pregnant again within weeks of delivery, even while nursing, and her kittens can breed from their first season at around four months. Cats Protection runs low-cost neutering schemes.
- Queen's extra food (advanced): late pregnancy needs about 1.5 times normal calories, and peak lactation (weeks 3 to 4 of nursing) roughly 1 plus 0.5 times the number of kittens, so a queen feeding four kittens eats around three times her usual amount. Free-feed kitten food throughout.
- Week-by-week table (advanced): the dates of each week of the pregnancy with what to expect and do, and the current week marked. A guide, not veterinary advice.
Source and further reading: PDSA pet health advice.