When will your dog have her puppies?
Enter the breeding or ovulation date: the expected whelping day, the window and when to check.
For general information only, not veterinary advice. A due date is an estimate; ask your veterinarian to confirm the pregnancy and plan the birth, and call at once if something looks wrong. How we check our calculators.
Ovulation, LH and diestrus dates come from tests your veterinarian runs and give a much narrower window than a breeding date.
What the due date means
A dog’s pregnancy lasts about two months, but the day you start counting changes the answer by days. Cornell notes that breeding dates are often inaccurate, so the breeding date is only loosely tied to when the eggs were fertilized. Ovulation and the LH surge that triggers it are biological events your veterinarian can find with progesterone blood tests, and they pin the due date down far better. The calculator therefore asks which date you have and uses the interval the sources give for it.
The four ways to count
From ovulation: 63 days, plus or minus 1 (Colorado State Veterinary Health System); Cornell’s Riney Canine Health Center says 63, plus or minus 1 to 2 days, from the progesterone-based ovulation date. From the LH peak: 65 days, plus or minus 1 (Colorado State); the MSD Veterinary Manual gives 64 to 66 days from the initial progesterone rise or the LH surge. From the first day of diestrus: 56 to 58 days (MSD Veterinary Manual). From a single breeding: about 63 days with a range of 57 to 72 (Purdue Extension); the MSD Veterinary Manual gives 58 to 72, and Cornell writes 63 plus or minus 7 days from the first breeding. The calculator centres the breeding window on day 63 and prints the full 57 to 72.
Worked example
Take March 1 as the date you enter. As an ovulation date it gives a due date of May 3 with a window of May 2 to May 4. As the LH surge date it gives May 5, window May 4 to May 6; as the first day of diestrus, April 27, window April 26 to April 28. As a single breeding date the same day gives May 3, but the window runs from April 27 to May 12, a spread of 16 calendar days against 3 for the ovulation date. Along the way the veterinary checks fall on these dates for a breeding on March 1: ultrasound March 29 to March 31, skeletons first visible on X-ray April 12 to April 15, a puppy-count X-ray from April 25, and daily temperature checks from April 20, a week before the earliest date.
How the milestones are chosen
Only milestones that a veterinary source dates in days are shown. Purdue Extension gives the ultrasound at 28 to 30 days after breeding; the MSD Veterinary Manual says ultrasound works best at 25 to 35 days and that a result before 21 days can be a false negative. X-ray shows the skeleton from about day 42 to 45, and a count is most reliable from day 55. Because those sources count from breeding, the calculator shows the day-count milestones for breeding and ovulation dates only; for an LH or diestrus date it shows the temperature check, which is tied to the whelping window. The temperature drop itself is not a date: the MSD Veterinary Manual reports it 8 to 24 hours before whelping.
Limits of a due date
The MSD Veterinary Manual is blunt: breeding dates and conception dates do not correlate closely enough to permit accurate prediction of whelping dates, and predicting gestation length without prior ovulation timing is difficult. If you have only one breeding date, expect to wait anywhere in a two-week window. Cornell lists a simple check near term: a vet can test progesterone, which usually drops suddenly within 24 hours of giving birth. The temperature drop is not guaranteed, as Colorado State sees it in about 80 percent of bitches. Finally, a normal pregnancy does not replace veterinary care. High-risk breeds especially should have a plan: Purdue suggests breeding timing for any breed with a high risk of whelping complications.
How long is a dog pregnant?
About 63 days, or two months, counted from ovulation. Purdue Extension and Cornell both give 63 days. The number depends on where you start counting: Colorado State puts whelping at 63 days, plus or minus 1, after ovulation and 65 days, plus or minus 1, after the LH peak, and the MSD Veterinary Manual gives 56 to 58 days from the first day of diestrus. Counted from a single breeding the spread is far wider, 57 to 72 days at Purdue.
When can a vet confirm a dog is pregnant?
Purdue Extension says an abdominal ultrasound 28 to 30 days after breeding can show fetal heartbeats. The MSD Veterinary Manual says ultrasound is best done at 25 to 35 days of gestation and warns that before 21 days a false negative can occur. Colorado State calls three to four weeks after breeding the most accurate time. For the example date of March 1, 28 to 30 days after breeding is March 29 to March 31.
When is an X-ray useful?
Skeletons are not visible on routine X-rays until about day 42 to 45 and are quite prominent by day 47 to 48 (MSD Veterinary Manual). For counting puppies, Purdue asks for radiographs on or after day 55 and the MSD Veterinary Manual says late radiography, after day 55, is the best way to determine litter size; Colorado State says the count is most accurate about one week before the due date. Knowing the number tells you whether she is done giving birth.
How does the temperature drop predict labor?
Purdue Extension suggests taking her rectal temperature once a day during the week before whelping. About 24 hours before whelping it drops from the normal 100 to 102.5 °F to about 99 °F. The MSD Veterinary Manual reports a mean of 98.8 °F (range 98.1 to 100 °F) 8 to 24 hours before whelping, and Colorado State says about 80 percent of bitches show the drop, typically 2 to 3 °F below baseline. Because 20 percent do not, a missing drop does not mean she is not close.
What are the signs that labor is starting?
Purdue lists restlessness, panting, enlarged nipples, decreased appetite and nesting. Cornell says these signs usually come 6 to 12 hours before the birth. Purdue describes stage 1 of labor as lasting 12 to 24 hours, with uterine contractions that may not be visible. Once strong contractions begin a puppy should arrive within 1 hour, and a gap of 45 to 60 minutes between puppies is a reason to call the veterinarian.
What is an emergency during whelping?
Purdue Extension names one clearly: a greenish or black discharge from the vulva before a puppy has arrived points to premature separation of the placenta, and the puppies have lost their oxygen supply, so it is a true emergency. Call your veterinarian or an emergency clinic at once. Also call if strong contractions go on for an hour without a puppy, as above.
How should I feed a pregnant dog?
Purdue says her needs do not change from breeding until pregnancy is diagnosed if she is on a quality, balanced food at a healthy weight, and that after diagnosis her calories should gradually rise by 35 to 50 percent, with a switch to a calorie-dense food such as puppy food. Her stomach capacity shrinks as the puppies grow, so smaller, more frequent meals help. Ask your veterinarian for the plan for your dog; the pet calorie calculator gives her resting numbers but not a pregnancy diet.
For general information only, not veterinary advice; consult your veterinarian about your dog’s pregnancy and birth. Sources: Purdue University Extension, VA-29-W “What to Expect When Your Dog is Expecting” (J. Koziol, DVM, DACT, January 2021); Colorado State University Veterinary Health System, “Pregnancy and Whelping for Dogs” (F. Hollinshead, May 9, 2022); Cornell University Riney Canine Health Center, “The normal whelping process”; MSD Veterinary Manual, “Pregnancy Determination in Small Animals” and “Whelping and Queening in Dogs and Cats” (A. P. Davidson, full review June 2025), all read October 28, 2026. Related: pet calorie calculator, dog age calculator, due date calculator for people and date calculator. How we check our calculators.