How this calculator works
The clinical reference describes gestation lasting 59 to 72 days. This page uses 68 days as an explicit planning assumption within that range. Litter size affects timing, so a single calendar date has limited precision. Date arithmetic uses whole calendar days in UTC, so daylight-saving changes do not shift the result. A negative elapsed value means the reference date is still ahead; a negative remaining value means the estimate has passed.
Formula
Due date = reference date + assumed gestation days. Reverse mode subtracts the same duration. The default is 68 days, with a 59 to 72 day planning window. Days remaining = due date - observation date. The window is not a guarantee.
Worked example
A breeding date of 1 January 2026 gives a 68-day estimate of 10 March. The 59 to 72 day window runs from 1 to 14 March.
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Frequently asked questions
Does the estimated date confirm pregnancy?
No. A recorded mating may not result in pregnancy. Veterinary examination and appropriate imaging are needed for confirmation.
Can I work backwards from a due date?
Yes. Choose breeding-date mode. The answer is the date implied by the assumed duration, not proof of the actual conception day.
Why might birth occur outside the window?
Breeding and ovulation dates can differ, and litter size, breed and individual history influence timing. Arrange monitoring with your veterinarian instead of using the window as a safety test.