Dog Pregnancy Calculator
With date of mating Fri, October 2, 2026, expected litter size 6, dog pregnancy comes to Fri, December 4, 2026 — whelping date. It is reached in 7 steps, the last of which is 2026-10-02 + 63, and each one is printed on the page with its numbers filled in. The formula is the one published by Merck Veterinary Manual, not an approximation fitted to it.
Whelping date from the mating date, on the 63-day canine gestation, with the dates each check and each stage of the pregnancy falls due.
Formula and sources checked · How we check
Date of mating 2026-09-01, Expected litter size 6
Fri, December 4, 2026
Whelping date for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- Whelping date
2026-10-02 + 63Fri, December 4, 2026- Earliest normal
2026-10-02 + 58Sun, November 29, 2026- Latest normal
2026-10-02 + 68Wed, December 9, 2026- Ultrasound confirms pregnancy from
2026-10-02 + 25Tue, October 27, 2026- X-ray can count the puppies from
2026-10-02 + 45Mon, November 16, 2026- Set up the whelping box by
2026-10-02 + 55Thu, November 26, 2026- Typical time from first to last puppy
max(2, 6 * 0.75)4.5 h
Worked example
A mating on 1 September 2026 gives a whelping date of 3 November, with the normal window running 29 October to 8 November. The 63 days are counted from mating, which is why the window is ten days wide — ovulation can lag the mating by up to a week.
How to work it out yourself
- 1.Use the first mating date if there were several. Sperm survive several days in the reproductive tract, so the earliest date gives the widest and safest window.
- 2.Confirm by ultrasound from about day 25. Before that a pregnancy cannot be seen reliably, and a negative result too early means nothing.
- 3.X-ray from day 45, once the puppies' skeletons have mineralised. It gives a puppy count, which is the single most useful thing to know during whelping — you know when she has finished.
- 4.Set the whelping box up a week ahead so she settles in it rather than choosing a wardrobe on the night.
- 5.A temperature drop below about 37.8 °C usually comes 12 to 24 hours before labour. Taking it twice a day from day 55 is the best warning available.
The formula
- Whelping date
2026-10-02 + 63 - Earliest normal
2026-10-02 + 58 - Latest normal
2026-10-02 + 68 - Ultrasound confirms pregnancy from
2026-10-02 + 25 - X-ray can count the puppies from
2026-10-02 + 45 - Set up the whelping box by
2026-10-02 + 55 - Typical time from first to last puppy
max(2, 6 * 0.75)
Source: Merck Veterinary Manual — management of reproduction in dogs, gestation length, Concannon PW. Reproductive cycles of the domestic bitch. Anim Reprod Sci 2011;124:200-10, AVMA — dog breeding and reproduction guidance for owners
Questions people actually ask
- How long are dogs pregnant?
- 63 days from ovulation, but 58 to 68 days from mating — because ovulation can happen up to a week after. Measured from the luteinising hormone surge, which a vet can test for, the 63 days are remarkably consistent across breeds and litter sizes.
- When can you tell if a dog is pregnant?
- Ultrasound from about day 25, which also shows heartbeats. A relaxin blood test works from day 21 to 25. X-ray from day 45 counts the skeletons, and that count is what tells you during whelping whether she has finished.
- What are the signs a dog is about to give birth?
- Rectal temperature dropping below about 37.8 °C, 12 to 24 hours ahead. Then restlessness, nesting, refusing food and panting. Active straining should produce a puppy within an hour; longer than that needs a vet immediately.
- How long does whelping take?
- Usually 20 to 60 minutes between puppies, so a litter of six takes four to six hours. Rests of up to two hours between puppies can be normal. More than two hours of rest with puppies still inside, or 30 minutes of hard straining with nothing produced, is an emergency.
- Is 58 days too early?
- It is at the edge of normal when counted from mating, and puppies born before day 58 from ovulation often do not survive without intensive care. If you know the ovulation date rather than only the mating date, that is the one to count from.
Related
- Puppy WeightAdult weight from a puppy's weight and age, on growth curves that differ by breed size — small dogs finish at eight months, giant breeds at eighteen.
- Dog Calorie CalculatorDaily calories a dog needs, from the resting energy requirement formula vets use — 70 x weight^0.75 — multiplied by the factor for its life stage.
- Due Date CalculatorEstimated due date from a last menstrual period or a known conception date, with the current gestational age.
- Dog Chocolate ToxicityTheobromine dose a dog has taken from the type and weight of chocolate eaten, against the published thresholds where signs begin and where they turn serious.
- Ovulation CalculatorOvulation day and the six-day fertile window from your last period, counted back from the next period rather than forward from day 14.
- Period CalculatorYour next six periods from the last one, with the prediction window widening the further out it goes — because cycle length varies month to month.
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