How dog due dates are calculated
A dog's pregnancy lasts about 63 days from ovulation, roughly nine weeks. The complication is that breeding and ovulation don't always happen on the same day. Dog eggs need a couple of days to mature after they're released, and sperm can survive in the reproductive tract for several days, so a mating can take place days before or after the eggs are ready. That is why a due date counted from the breeding date comes with a wide window: most litters arrive 58 to 68 days after mating, and the Merck Veterinary Manual gives an outer range of 58 to 72 days from the first breeding.
Breeders who use progesterone blood tests to pinpoint ovulation get far more precise dates. Whelping is typically 63 ± 1–2 days after ovulation or 65 ± 1–2 days after the LH surge, which comes about two days before ovulation. Choose the date type that matches what you know.
The formula
from ovulation date: due = ovulation date + 63 days (window 61–65)
from LH surge date: due = LH surge date + 65 days (window 63–67)
days along = today − breeding (or ovulation) date
Example: bred on June 1, 2026
For a dog bred once on Monday, June 1, 2026, using the breeding date:
| Milestone | Day | Date |
|---|---|---|
| Breeding | 0 | Jun 1 |
| Implantation | 18–21 | Jun 19 – Jun 22 |
| Ultrasound window | 25–35 | Jun 26 – Jul 6 |
| Start increasing food | 35+ | From Jul 6 |
| X-ray shows skeletons | 45+ | From Jul 16 |
| Whelping box, temperature checks | 55–58 | Jul 26 – Jul 29 |
| Estimated due date | 63 | Mon, Aug 3, 2026 |
| Normal whelping window | 58–68 | Jul 29 – Aug 8 |
| Call the vet if no labor | 68 | Aug 8 |
The three trimesters
Weeks 1–3 (days 0–21)
Fertilized eggs travel to the uterus and implant around days 18–21. There are usually no visible changes, though some dogs have mild morning sickness or a slightly reduced appetite around week three. Keep feeding and exercise normal.
Weeks 4–6 (days 22–42)
This is the window to confirm the pregnancy with an ultrasound or relaxin test. Fetuses grow quickly, and her belly and nipples may start to enlarge. From about week five or six, begin a gradual switch to a puppy or all-life-stages food.
Weeks 7–9 (days 43–63)
Her abdomen grows noticeably and you may see puppies moving. An x-ray after day 55 gives the best puppy count, which helps you know when she's finished whelping. Introduce the whelping box a week or two ahead so she's comfortable in it, and start taking her rectal temperature twice a day. Normal is about 100–102.5°F; a drop below about 99°F usually means labor within 12–24 hours.
Practical tips
- Book a vet check early. Confirm the pregnancy, discuss nutrition and parasite control, and ask what signs should prompt an emergency call.
- Avoid unprescribed supplements. Extra calcium during pregnancy can increase the risk of dangerously low calcium (eclampsia) after whelping.
- Know your emergency plan. Save the number of an emergency clinic that's open nights and weekends before the due date.
- Watch the clock during labor. Call a vet for 30 minutes of hard straining without a puppy, more than 2–4 hours between puppies, or green-black discharge before the first puppy.
This calculator gives estimates for planning and is not veterinary advice. Pregnancy and whelping should be supervised by a veterinarian.
Frequently asked questions
How long are dogs pregnant?
About 63 days, or nine weeks, counted from ovulation. Counted from the breeding date, puppies usually arrive between 58 and 68 days, and the Merck Veterinary Manual gives an outer range of 58 to 72 days from the first mating. The range is wide because sperm can survive several days waiting for eggs to mature.
How accurate is a dog due date?
If ovulation was pinpointed with progesterone testing, whelping is very predictable, usually 63 days after ovulation give or take a day or two, or 65 days after the LH surge. From a breeding date alone, the estimate can be off by several days in either direction.
When can a vet confirm a dog is pregnant?
An ultrasound can usually confirm pregnancy from about 25 to 35 days after breeding, when heartbeats become visible. A relaxin blood test works from roughly 25 to 30 days. An experienced vet may feel the developing pregnancies by palpation around days 28 to 35. X-rays show puppy skeletons from about day 45 and give the most reliable count after day 55.
What are the signs that my dog is about to give birth?
Restlessness, nesting, loss of appetite, panting and shivering are common in the last day or two. The most useful sign is a drop in rectal temperature below about 99°F (37.2°C), which typically happens 12 to 24 hours before labor. Start taking her temperature twice a day about a week before the due date.
When should I call the vet during whelping?
Call if there is no sign of labor by about 68 days after breeding, if she strains hard for 30 minutes without producing a puppy, if more than 2 to 4 hours pass between puppies, if there is green or black discharge before the first puppy, or if she seems weak or in severe pain.
Should I change my pregnant dog's food?
Usually not for the first five weeks. From about week five or six, most vets recommend gradually switching to a high-quality puppy or all-life-stages food and increasing the amount, so that by whelping she eats roughly 25 to 50% more than her normal maintenance amount. Ask your vet about her specific needs and avoid extra calcium supplements unless prescribed.
Rates and figures last checked September 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.