Free tool
Dog Pregnancy Calculator NZ
Dogs are pregnant for 58–72 days from the first mating, or 64–66 days from the LH surge if your vet timed ovulation. Enter the date you have to see the expected whelping window.
The first day she accepted the male. Gives the widest window, because mating dates don't pin down ovulation.
Choose the date you have and enter it to see the expected whelping window.
Vet checks during pregnancy
Merck gives these as days of pregnancy. Ask your vet which date they are counting from.
- Ultrasound: Best at 25–35 days of pregnancy; may miss a pregnancy before day 21.
- Relaxin blood test: Detects pregnancy after 22–27 days.
- X-ray: Skeletons show from about day 42–45; after day 55 is the best time to count puppies.
When to call the vet during whelping
Merck counts any of these as a prolonged or difficult birth. Call your vet, or an after-hours vet at night, straight away:
- No puppy within 24–36 hours of her temperature dropping
- More than 30 minutes between puppies while she is clearly having contractions
- More than 2 hours between puppies with no contractions
- More than 4 hours of labour (strong or weak) with no puppy
- Whelping lasting more than 24 hours in total
- Dark green or smelly discharge before a puppy is born
Keep reading
- Dog Breed Prices NZ — typical puppy prices by breed
- Feeding Calculator NZ — daily food for dogs and puppies
Frequently asked questions
How long are dogs pregnant?
The Merck Veterinary Manual gives 58–72 days from the first day the female accepted mating, 64–66 days from the LH surge or first rise in progesterone (measured by your vet), and 56–58 days from the first day of diestrus. The range from mating is wide because a mating date doesn't show exactly when she ovulated.
Can I work out my dog's due date from the mating date?
Only roughly. Merck notes that mating dates don't predict the whelping date accurately, which is why the calculator shows a 15-day window for a mating date. If your vet timed ovulation with progesterone or LH testing, enter that date instead for a 3-day window.
How soon can a vet confirm my dog is pregnant?
Merck says ultrasound works best at 25–35 days of pregnancy and can give false negatives before day 21. A blood test for relaxin can detect pregnancy after 22–27 days. Puppies' skeletons show on an X-ray from about day 42–45, and an X-ray after day 55 is the best way to count them.
What are the signs my dog is about to give birth?
In most dogs, rectal temperature drops to about 36.7–37.8 °C 8–24 hours before whelping. Merck also lists a relaxed, softer area under the tail (the perineum) and swollen mammary glands as subtle signs that delivery is near.
When should I call the vet during whelping?
Merck lists these as signs of a prolonged or difficult birth: no puppy within 24–36 hours of the temperature drop; more than 30 minutes between puppies while she is clearly having contractions; more than 2 hours between puppies without contractions; more than 4 hours of labour with no puppy; whelping lasting over 24 hours in total. Dark green or smelly discharge before a puppy is born can mean a placenta has separated. Call your vet or after-hours vet if you see any of these.
Sources
- Merck Veterinary Manual — Whelping and Queening in Dogs and Cats (gestation length, temperature drop) — checked 9 November 2026
- Merck Veterinary Manual — Pregnancy Determination in Dogs and Cats (ultrasound, relaxin, X-ray) — checked 9 November 2026
- Merck Veterinary Manual — Dystocia in Small Animals (when whelping is prolonged) — checked 9 November 2026
- Concannon PW (1986). Canine pregnancy and parturition. Vet Clin North Am Small Anim Pract 16(3):453–75 — checked 9 November 2026
Important:this is general information, not veterinary advice. Have a NZ vet check a pregnant dog, and plan where you'll go if whelping goes wrong after hours.