Dog & Cat Pregnancy Calculator — Whelping Due Date & Calendar

The Formula

The due date is calculated by adding the species-specific gestation period to the breeding date. Dogs average 63 days (range 58–68), while cats average 65 days (range 63–67).

Variable Definitions

How to Use This Calculator

1. 1

   Select whether the pet is a Dog or Cat.

2. 2

   Enter the breeding (mating) date.

3. 3

   View the estimated due date and expected date range.

4. 4

   Check how many days remain until the due date, and what trimester the pregnancy is in.

5. 5

   Review the week-by-week calendar for a full timeline of the pregnancy.

Common Applications

• Breeding management — estimate whelping (dog) or queening (cat) due dates to prepare for birth and arrange veterinary support in advance
• Pregnancy monitoring — track trimesters and week-by-week progress to ensure the mother receives appropriate nutrition and care at each developmental stage
• Veterinary appointment scheduling — know when to schedule ultrasound (day 25-30), X-ray (day 45+), and pre-labor wellness checkups
• Emergency preparedness — identify when the due date range has passed without labor and veterinary intervention may be needed to ensure safe delivery

Dog gestation averages 63 days; cat gestation averages 65 days. Both are divided into three trimesters.

Understanding the Concept

Canine and feline gestation periods are much shorter than human pregnancy, lasting approximately 9 weeks. The timing is remarkably consistent across breeds, though individual variation is normal. For dogs, gestation averages 63 days from ovulation (not from breeding date — there can be a 2–4 day lag since canine sperm can survive for several days in the reproductive tract). For cats, gestation averages 65 days from breeding. Pregnancy is divided into three trimesters. During the first trimester (days 1–21), the fertilized eggs implant in the uterine lining and the embryos begin organ development. The second trimester (days 22–42) is a period of rapid growth where the fetuses become recognizable as puppies or kittens and their skeletons calcify. In the third trimester (day 43 to birth), the fetuses complete their development and positioning for birth occurs. A veterinarian should confirm pregnancy via ultrasound (day 25–30) or palpation (day 21–28). X-rays after day 45 can confirm the number of fetuses once their skeletons have calcified. Signs of imminent labor include nesting behavior, restlessness, drop in body temperature (dogs: below 100°F / 37.8°C), and appetite loss.

Frequently Asked Questions

Sources & References