A dog’s pregnancy lasts 63 days counted from ovulation, and anywhere from 57 to 72 days counted from mating — the same pregnancy, two very different answers. This calculator gives the due date, the window it really sits in, and a dated list of the points where a vet can confirm the pregnancy and count the puppies.
Dog due date calculator
Enter the mating date to get the due date and the window it sits in. If your vet timed ovulation by progesterone testing, entering that date instead narrows the answer from two weeks to three days.
Your due date, the window around it and a dated list of pregnancy milestones will appear here.
Dates only, not veterinary advice. Canine gestation is 65 ± 1 days from the preovulatory LH surge, and 57–72 days when timed from mating instead, because sperm survive several days and ovulation timing varies (Concannon, Parturition prediction and timing of canine pregnancy). Ultrasound and radiography timings follow England et al. A due date is an estimate; whelping outside the window is a reason to speak to your vet.
Mating date or ovulation date?
Canine gestation is one of the most tightly fixed intervals in domestic animals, but it is fixed to ovulation rather than to mating. Measured from the preovulatory surge in luteinising hormone, whelping follows at 65 ± 1 days; ovulation itself occurs about two days after that surge, which is where the familiar 63-day figure comes from. Measured from a mating, the same pregnancies range from 57 to 72 days (Concannon).
The reason is that mating and ovulation are not the same event. Dog sperm remain viable in the reproductive tract for several days, so a mating that happens well before ovulation can still produce a pregnancy, and a bitch may be mated again after she has already ovulated. A due date built on a mating date inherits all of that slack. This is why the calculator above shows a window rather than a single day, and why a progesterone-timed ovulation date narrows the answer from about a fortnight to three days.
What a dog gestation calculator can and cannot tell you
A gestation calculator is arithmetic on a date, and it is accurate to exactly the quality of the date you give it. It can tell you when to have a whelping box ready, when a scan would be worth booking, and when an X-ray would show a puppy count. It cannot tell you how many puppies there are, whether the pregnancy is viable, or whether a whelping is going normally. Those need a vet, and no calculator on any site is a substitute for one.
The milestones the dates are anchored to
Every milestone in the timeline above is measured from the LH surge, because that is what the underlying research measures. The gestational sac becomes visible on ultrasound at 17 to 20 days and the embryonic heartbeat at 23 to 25 days (England et al.). Fetal skeletons mineralise enough to show on radiography at about 43 to 46 days, which is the point at which the litter can be counted. Whelping follows at 64 to 66 days. When only a mating date is known, these dates are left blank rather than estimated, because the two-week uncertainty in the due date applies to every one of them.
Gestation length does not vary by breed
Canine gestation length is the same across breeds. A Chihuahua and a Great Dane both carry for 63 days from ovulation, and there is no breed-specific due-date formula worth applying. Litter size, birth weight and the likelihood of a difficult whelping do differ substantially by breed and size — but the length of the pregnancy does not, which is why this calculator asks for dates and not for a breed.
After the puppies arrive
A whelping date is the start of the part this site was built for. Newborn puppies are weighed daily at first and then weekly, and a puppy that is not gaining is the earliest signal anything is wrong. Once they arrive, the puppy weight calculator estimates the adult weight each one is heading for from its age and current weight, and the puppy growth chart by age gives the month-by-month ranges to track them against. The growth data behind both is published in full, as are the gestation figures on this page.
Frequently asked questions
How long are dogs pregnant?
Dogs are pregnant for 63 days on average, but that figure is only reliable when it is counted from ovulation. Timed from the preovulatory LH surge, canine gestation is 65 plus or minus one day in nearly every pregnancy. Timed from mating, full-term gestations are reported anywhere from 57 to 72 days, because sperm survive several days in the reproductive tract and the interval between mating and ovulation varies between bitches.
Why does the due date from a mating date cover two weeks?
Because gestation is fixed to ovulation, not to mating. A bitch can be mated several days before or after she ovulates, and dog sperm remain viable long enough for either to result in a pregnancy. That uncertainty is carried straight into the due date. A progesterone-timed ovulation date removes it, which is why this calculator narrows the answer to three days when you supply one.
When can a vet confirm a dog is pregnant?
The gestational sac becomes visible on ultrasound 17 to 20 days after the LH surge, and the embryo and its heartbeat can be detected at 23 to 25 days. Ultrasound confirms that a pregnancy exists and is viable, but it is not a reliable way to count the puppies.
When can the puppies be counted?
Radiography shows the puppies’ skeletons from about 43 to 46 days after the LH surge, once enough bone has mineralised to be visible. An X-ray at that stage is the only reliable way to know how many puppies to expect, which matters during whelping because it tells you when the litter is complete.
Is the due date different for different breeds?
No. Canine gestation length does not vary by breed. A Chihuahua and a Great Dane carry for the same 63 days from ovulation. Litter size, birth weight and whelping difficulty all differ by breed and size, but the length of the pregnancy does not.
Where these numbers come from
The gestation intervals on this page come from the veterinary reproduction literature rather than from breeder convention. The 65 ± 1 day interval from the LH surge, and the 57 to 72 day spread from insemination, are Concannon’s; the ultrasound and radiography timings are England’s. Nothing here is a figure this site has estimated. Where a number is a range in the source, it is shown as a range here.