Dog Pregnancy Due Date Calculator
Veterinary figures last checked October 2, 2026.
A dog first bred on Nov 1 is most likely to whelp around Jan 3, day 63, within a window of days 56 to 70.
Example shown. Pick your own date below.If she was bred more than once, use the first date she accepted the male.
How we got this (example: first breeding Nov 1, 2026)
- Start from the first breeding (mating) date: Sunday, November 1, 2026.
- Add the average gestation of 63 days for the most likely date: Nov 1, 2026 + 63 days = Jan 3, 2027 (Cornell Riney Canine Health Center)
- Cornell's window runs from day 56 to day 70: Nov 1, 2026 + 56 days = Dec 27, 2026; Nov 1, 2026 + 70 days = Jan 10, 2027 (Cornell Riney Canine Health Center)
- Past day 70 from a breeding date counts as a prolonged pregnancy, so call your vet if there is no labor by then: Nov 1, 2026 + 70 days = Jan 10, 2027 (Merck Veterinary Manual, dystocia)
The idea behind it: A dog's pregnancy is counted in days from a known date, so the due date is that date plus the published number of days. A mating date gives the widest window because sperm can live for days inside her, so she may conceive well after the mating.
Pick a date to see the due-date window and milestones.
Enter the first breeding date, or a date your vet measured, to get the window when puppies are most likely and the dates for ultrasound, X-ray and the last-week temperature checks.
This is a planning aid, not a diagnosis. Confirm the pregnancy and the due date with your veterinarian, and call your vet at once if anything during pregnancy or whelping worries you.
How this is calculated
Due date = the date you enter + the number of days the veterinary sources give for that kind of date (Merck Veterinary Manual, checked Oct 2, 2026).
Days used for each kind of date
| Date you enter | Days to whelping | Source |
|---|---|---|
| First breeding (mating) date | 63 on average; 56 to 70 (Merck: 58 to 72) | Cornell: 63 days plus or minus 7 from the first breeding (days 56 to 70). Merck: 58 to 72 days from the first breeding. |
| Ovulation date (timed by your vet) | 63 on average; 61 to 65 | Cornell: 63 days plus or minus 1 to 2 from ovulation (days 61 to 65). |
| LH surge or first progesterone rise (vet blood test) | 64 to 66 | Merck: 64 to 66 days from the LH surge or the first rise in progesterone above baseline. |
| First day of diestrus (vet vaginal smear) | 56 to 58 | Merck: 56 to 58 days from the first day of diestrus. |
Example: a first breeding on Sunday, November 1, 2026 gives an average date of Sunday, January 3, 2027, a window from Sunday, December 27, 2026 to Sunday, January 10, 2027, and day 70 on Sunday, January 10, 2027.
The breeding-date window is wide on purpose. Merck says fresh semen can survive 9 or more days in the female and eggs need several days after ovulation to mature, so conception can follow the mating you saw by days. A vet's progesterone or LH test, or a vaginal smear that marks the first day of diestrus, cuts the window to about three to five days.
The calculator does not account for breed, litter size or the mother's health (Merck lists breed, parity and litter size as factors), and a vet's ultrasound or X-ray replaces the estimate.
Milestones during the pregnancy
Gestation days as published by Merck, which counts from the LH surge: its ultrasound table gives the days left before birth as 64 to 66 minus the gestation day. The calculator shifts these for your date type (about 2 days for an ovulation or breeding date, 8 for diestrus) and puts real dates on them. From a breeding date they are approximate by several days.
| Gestation day (from the LH surge) | What happens or what your vet can do |
|---|---|
| 18 | Implantation. Merck: embryos implant in the uterus at about 18 days. |
| 21 to 35 | A vet may feel the early swellings. Merck: small swellings along the uterus can be felt by about day 21 in a cooperative dog; after day 35 to 38 they become hard to feel until late pregnancy. |
| 22 to 27 | Relaxin blood test becomes possible. Merck: a commercial relaxin test detects placentas after 22 to 27 days. |
| 25 to 35 | Best window for an ultrasound. Merck: ultrasound is best done at 25 to 35 days; before 21 days a pregnant dog can test negative. |
| 42 to 45 | Puppy skeletons show on X-ray. Merck: the skeleton is not visible on routine X-rays until about day 42 to 45, and is clear by day 47 to 48. |
| 55 | Best time to count puppies. Merck: an X-ray after day 55 is the best way to count the litter. |
| Last 24 hours | Temperature drop. Merck: rectal temperature falls to about 98.8 F (98.1 to 100 F) in most dogs 8 to 24 hours before whelping. |
Signs of trouble during whelping
From Merck's dog-owner guide, its dystocia chapter, and Cornell. Call your veterinarian if you see any of these:
- No puppy within 24 hours of the temperature dropping below 100 F (Merck).
- Strong contractions or active labor for more than 1 to 2 hours without a puppy (Merck).
- More than two hours between puppies (Cornell).
- A rest of more than 4 to 6 hours in the middle of labor (Merck).
- Obvious pain or illness in the mother, or abnormal discharge; dark green or foul-smelling discharge before the first puppy (Merck).
- No labor by day 70 after a known breeding date (Merck).
Why we built it this way
The dog pregnancy calculators we looked at take only a mating date, add 63 days and show one date, without saying where the number comes from. This one accepts the dates a vet can measure, shows the published window for each, gives the day-70 date when a vet should hear from you, and puts real dates on the ultrasound, X-ray and temperature milestones, with the source beside each one.
Questions people ask
How long are dogs pregnant?
About two months. Cornell's College of Veterinary Medicine gives an average of 63 days from ovulation. Counted from the first breeding, Cornell says 63 days plus or minus 7, and the Merck Veterinary Manual gives 58 to 72 days. With hormone timing by a vet, Merck gives 64 to 66 days from the LH surge.
Why is the due date a window and not one day?
Because mating is not conception. Merck notes that fresh semen can live in the female for 9 or more days, and that eggs are released 2 to 3 days after the LH surge and need another 2 to 3 days to mature. So puppies can be conceived days after the breeding you saw, and Merck says breeding dates do not match whelping dates as closely as ovulation does.
How can I get a more exact due date?
Ask your vet about ovulation timing. Progesterone or LH blood tests, or vaginal smears that show the first day of diestrus, narrow the window to a few days: 64 to 66 days from the LH surge, or 56 to 58 days from the first day of diestrus (Merck). Choose that date type in the calculator if you have it.
When can a vet confirm the pregnancy?
Merck says ultrasound works best at 25 to 35 days, and may miss a pregnancy before day 21. A relaxin blood test can detect placentas after 22 to 27 days. A vet may feel the early swellings in the uterus at about day 21, but they become hard to feel after day 35 to 38.
When can I find out how many puppies there are?
Merck says an X-ray late in pregnancy, after day 55, is the best way to count the litter. Skeletons are not visible on routine X-rays until about day 42 to 45.
What are the signs labor is close?
A drop in rectal temperature. Merck says it falls to about 98.8 F (range 98.1 to 100 F) in most dogs 8 to 24 hours before whelping, and Cornell says it drops below 99 F within 24 hours of birth. Cornell gives a normal dog temperature of 100 to 102.5 F. Ask your vet when to start checking and how.
When should I call the vet during whelping?
Cornell says to contact your vet if more than two hours pass between puppies. Merck's dog-owner guide lists: no birth within 24 hours of the temperature drop below 100 F, strong contractions or active labor for more than 1 to 2 hours with no puppy, a rest of more than 4 to 6 hours during labor, obvious pain, and abnormal discharge. Merck's dystocia chapter adds dark green or foul-smelling discharge before the first puppy. If you are unsure, call.
What if she goes past the due date?
Merck's dystocia chapter considers a pregnancy longer than 70 days from a known breeding date prolonged, while its whelping chapter gives a normal range up to 72 days. The calculator uses the earlier date, day 70, for a breeding-date entry. Call your vet if it arrives without labor, or sooner if anything seems wrong.
Sources
- Merck Veterinary Manual: Whelping and Queening in Bitches and Queens, by Autumn P. Davidson, DVM (updated Jun 2025; checked Oct 2, 2026)
- Merck Veterinary Manual: Pregnancy Determination in Bitches and Queens, by Autumn P. Davidson, DVM (updated Jan 2026; checked Oct 2, 2026)
- Merck Veterinary Manual: Breeding Management of Bitches, by Autumn P. Davidson, DVM (updated Jul 2025; checked Oct 2, 2026)
- Merck Veterinary Manual: Dystocia in Small Animals, by Clare M. Scully, DVM (updated Jul 2026; checked Oct 2, 2026)
- Merck Veterinary Manual, dog owners edition: Reproductive Disorders of Female Dogs (updated Sep 2024; checked Oct 2, 2026)
- Cornell University College of Veterinary Medicine, Riney Canine Health Center: The normal whelping process (checked Oct 2, 2026)
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