• The maximum lifespan of a muskrat is 3 years, in captivity up to 10 years. Muskrats live longer in captivity than in nature.
• In captivity it has lived about 3–4 years.
• Litters can contain up to 10–12 young.

Common muskrats typically live for two to four years, although the maximum lifespan can reach ten years, with a theoretical lifespan ranging from seven years and six months to ten years and nine months. The species reaches sexual maturity between ten months and one week and one year of age. Eyes open between two weeks and two weeks and two days; during the embryo stage, the offspring develops inside the mother. The young, after birth, are initially naked and blind, feeding solely on milk, and this infant stage lasts from one day to one month and one week. Following this, the animal enters the adult stage, becoming a reproductive and independent muskrat.