Dog and Cat Pregnancy Calculator
Choose the animal and enter the mating date – the calculator shows when the litter is expected, which day of pregnancy your dog or cat is on today and when an ultrasound or X-ray makes sense.
Source: MSD Veterinary Manual (Professional) – Whelping and Queening in Bitches and Queens (A. P. Davidson, 2025). Updated: .
How it is calculated
How the pregnancy calculator works
It adds the gestation length from the MSD Veterinary Manual, a standard veterinary reference, to the date you enter. Because gestation is stated differently depending on the starting point, the calculator asks what your date refers to:
- Dog, first mating: 58–72 days from the first day the bitch permitted breeding (Professional Version). The pet owner version gives about 62–64 days as a rule of thumb – shown here as the “most common range”.
- Dog, LH surge or progesterone rise (measured by your vet with a blood test): 64–66 days – much more precise.
- Dog, first day of diestrus (from vaginal cytology): 56–58 days.
- Cat, mating: 60–65 days according to the pet owner version; the Professional Version gives 64–66 days from the LH surge triggered by mating.
Worked example: dog, first mating on 1 September 2026: earliest 29 October 2026 (day 58), latest 12 November 2026 (day 72), most commonly between 2 and 4 November 2026.
Why the window is so wide
The MSD Manual states explicitly that breeding and conception dates do not correlate closely enough to predict whelping accurately. For more precision, ask your vet to track progesterone.
Check-ups
The table lists the times from the Manual’s pet owner version: in dogs the uterus can be palpated around day 21, ultrasound from day 25–35, the relaxin test from day 30–35, puppies show on X-rays from about day 45, and X-rays after day 55 are best for counting the litter. In cats pregnancy can be detected from day 21–30; in the last three weeks a queen needs about 25% more food.
Honest limits
The calculator does not replace your vet. It cannot detect false pregnancy, complications or breed-specific differences. Signs of labour, a long pause between puppies or an overdue date always need veterinary attention. No data is sent.
Frequently asked questions
How long is a dog pregnant?
About 62–64 days according to the MSD Veterinary Manual. Counted from the first mating, 58–72 days are possible; from the LH surge 64–66 days; from the first day of diestrus 56–58 days.
How long is a cat pregnant?
The pet owner version of the MSD Manual gives 60–65 days from mating. Pregnancy can be detected from day 21–30.
How accurate is a due date from the mating date?
Not very: mating and fertilisation can be days apart, which is why the calculator shows a range. Progesterone or LH testing at the vet makes it much more precise.
When can a dog pregnancy be seen on ultrasound?
According to the MSD Manual from day 25–35; the relaxin blood test is reliable from day 30–35. Puppies are visible on X-rays from about day 45.
What if my dog is past her due date?
Contact your vet. The calculator only shows averages and cannot judge whether mother and puppies are fine.
Sources and legal basis
- MSD Veterinary Manual (Professional) – Whelping and Queening in Bitches and Queens (A. P. Davidson, 2025)
- MSD Veterinary Manual (Pet Owner) – Management of Reproduction in Dogs
- MSD Veterinary Manual (Pet Owner) – Management of Reproduction of Cats
As of: · Editorial policy
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