Sources
- Gestation figures come from standard veterinary reproduction references, including the Merck Veterinary Manual and university veterinary teaching hospitals.
- Litter size figures follow Borge et al. (2011), a study of 10,810 litters across 224 breeds. C-section rates cite Evans and Adams (2010) and the VetCompass studies.
- Each page lists the sources behind its main claims, and links to them open in a new tab.
- Where research gives a range or is uncertain, we show the range or say so.
How the calculator works
The calculator adds a fixed number of days to the date you enter, using the figure for the chosen method: 63 days from ovulation, 65 from the LH peak, 57 from diestrus day 1, and a 56 to 70 day window from a mating date. Breed notes come from our breed database. No data you enter is sent to a server (see the privacy policy).
What we will not do
- Give calorie, dose or treatment figures that depend on the individual dog.
- Replace the advice of your veterinarian.
- Present estimates as certainties.
Corrections and updates
If you find an error, tell us and we will check it against the sources and fix it. Each page shows when it was last updated, and we review pages when new research or guidance appears.