How dog gestation calculator works
Dogs are pregnant for about 63 days — nine weeks — counted from mating (more precisely, from ovulation, which the mating date approximates). The calculator adds 63 calendar days to the mating date for the expected due date, and shows the realistic whelping window of 58 to 68 days, because healthy litters routinely arrive a few days either side of the average.
Enter the mating date and an optional "track as of" date (it defaults to today) to see where the pregnancy stands: day count, week of gestation, days remaining, and progress through the 63 days. A milestone timeline marks the practical checkpoints — implantation around day 21, the vet palpation window from day 28, ultrasound confirmation around day 30, countable X-ray skeletons from day 45, and the whelping box being ready by day 58.
The math is pure calendar arithmetic — no month-length guessing — so a January mating correctly rolls across February's shorter length. Because gestation length varies litter to litter, the tool treats day 63 as the center of a window, not a deadline: puppies arriving in the 58–68 day range are normal, and anything landing well outside it is a call-the-vet situation.