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Description and Physical Characteristics of Mice

By Katherine E. Quesenberry, DVM, MPH, DABVP (Avian),
Kenneth R. Boschert, DVM, DACLAM, Associate Director, Division of Comparative Medicine, Washington University

Adult mice typically weigh about 1 ounce (28 grams) and are approximately 2.5 to 3.5 inches (6 to 8 centimeters) long, not including the tail (see Table: Mice at a Glance). Male mice are typically larger than females. Pet mice are available in many colors and coat patterns due to specialized breeding. Coats can be smooth, curly, longhaired or a combination. The most common color variations include brown, black, tan, gray, and albino, with lighter and darker shades of these as well. The usual life span of mice is 1.5 to 2.5 years.

Mice at a Glance


1.5 to 2.5 years


20 to 40 grams

Length (including tail)

6 to 7 inches (15 to 18 centimeters)

Normal body temperature

98 to 101°F (36°C)

Heart rate

450 to 600 beats per minute

Estrous cycle

4 to 5 days

Duration of pregnancy

19 to 21 days

Litter size

10 to 12 young

Weaning age

21 to 28 days

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