How it's calculated
Due date = mating date + gestation days
gestation = 60 (small), 63 (medium), 64 (large) or 65 (giant) days counted from the breeding date. Normal whelping window ≈ mating + 58 to 68 days.
Common questions
How long are dogs pregnant?
Around 63 days from ovulation, though anywhere from 58 to 68 days is considered normal.
Can I rely on the breeding date for the due date?
It is a good estimate, but ovulation timing varies, so a vet's progesterone testing or ultrasound gives a more precise date.