When are the kittens due? Enter the first and last mating to get the queening window, the day of pregnancy and the dates for the confirming ultrasound and the litter X-ray.
Cat Pregnancy Calculator - Kitten Due Date and Calendar
When are the kittens due? Enter the first and last mating to get the queening window, the day of pregnancy and the dates for the confirming ultrasound and the litter X-ray.
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Cat due date from the mating dates
Enter the first mating, and the last one if the queen was with the tom for several days, and the cat pregnancy calculator returns the kitten due date, the usual queening window, the day and week of pregnancy, and the dates for the confirming ultrasound and the X-ray that counts kittens. A queen ovulates because she is mated, so the mating day stands in for the hormone test a dog would need, and the window is only 3 to 10 days wide.
Three dates, two of them optional
- First mating - the first day she was with the tom and mated. Breeders often leave the pair together for 2 to 3 days.
- Last mating - optional. Leave it empty for a single mating. The calculator accepts up to 7 days between the first and the last.
- Count days as of - optional. Empty counts from today; a date shows the day of pregnancy and the countdown on that day.
Cat gestation, summed up as four figures
64-66 days
From the LH surge that mating triggers to queening, per the Merck Veterinary Manual. This is the window the calculator prints.
65.6 days on average
The mean from the first or last mating in a review by Root Kustritz in Theriogenology, pooling several studies.
52 to 74 days
The full reported range. Kittens born before day 60 have decreased viability, which is why day 60 sits on the calendar.
4.0 kittens
The average litter in the same review. It varies by breed and does not grow with the number of matings.
The pregnancy calendar for a March 1 mating
The calendar the calculator builds for one mating on March 1. Palpation and ultrasound confirm a pregnancy from 21 to 30 days after breeding (Merck), the clearest ultrasound views come at day 25 to 35, and an X-ray after day 55 is the best way to count the litter.
| Milestone | Day after mating | Mating on March 1 |
|---|---|---|
| Palpation or ultrasound to confirm | 21-30 | March 22 to March 31 |
| Ultrasound, clearest view | 25-35 | March 26 to April 5 |
| X-ray to count kittens | after 55 | from April 26 |
| Viability threshold | 60 | April 30 |
| Usual queening window | 64-66 | May 4 to May 6 |
| End of the reported range | 74 | May 14 |
How a longer stay with the tom widens the window
Each extra day of mating adds a day at the far end of the window. The due date is the middle day.
| Matings | Window | Width | Due date |
|---|---|---|---|
| March 1 only | May 4 to May 6 | 3 days | May 5 |
| March 1 and 2 | May 4 to May 7 | 4 days | May 6 |
| March 1 to 3 | May 4 to May 8 | 5 days | May 6 |
| March 1 to 5 | May 4 to May 10 | 7 days | May 7 |
Facts about feline pregnancy that catch owners out
Kittens in one litter can have different fathers. Root Kustritz calls this superfecundation common in cats, so a queen that met two toms in the same heat can carry kittens from both, and the calculator's window then runs from the first mating with either.
A normal pregnant queen has no vulvar discharge, because the cervix stays closed. Discharge during the pregnancy is a reason to call the vet.
Unlike a dog, a queen can go into active labor while her progesterone is still above 1 ng/mL, so the progesterone test that predicts whelping in dogs tells you much less in cats.
By the time she gives birth a queen has typically gained 12 to 38% of her pre-pregnancy weight.
Who usually opens this calculator
Breeders with a planned mating enter both dates and use the calendar to book the ultrasound and the late X-ray. Owners whose cat slipped outside enter the first and last possible day, up to 7 apart, and let an ultrasound narrow the window; Merck dates late pregnancy in cats to within about 2 days. Foster carers with a pregnant stray have no mating date and should ask the vet for that ultrasound estimate.
Cat pregnancy questions, briefly
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