On average, what's the gestational period of a dog?

The normal gestation period in dogs is approximately 63 days from conception, although this can vary by several days. While this might seem like a straightforward answer, conception is often hard to determine. Sperm can live for several days inside the female, and eggs can remain fertile for up to 48 hours, which means the act of mating itself is not an exact measurement of gestation.

Source: American Kennel Group