How old is a rat in human years?

Childhood and puberty

Compared to humans, rats have a brief, accelerated childhood. Rats develop rapidly during infancy and become sexually mature at about 6 weeks of age. Humans, on the other hand, develop slowly and don't hit puberty until about age 12-13 years (range: 8 to 16 years).

Adolescence and adulthood

Rats become sexually mature at age 6 weeks, but reach social maturity several months later at about 5 to 6 months of age (Adams and Boice 1983). In adulthood, each rat month is roughly equivalent to 2.5 human years (Ruth 1935).

Female rats enter menopause between ages 15 and 18 months (Durbin 1966), while humans enter menopause between 48 and 55 years (eMedicine).

Life expectancy

Domestic rats live about 2 to 3.5 years (Pass and Freeth 1993). In a survey of pet rat lifespans in the UK, the average lifespan was 21.6 months, and 95% percent had died by age 3 years (Clark 2004). In contrast, wild rats living in the wild tend to live for less than one year: 95% of wild rats die before age 1 year (Davis 1948).

The worldwide human life expectancy of humans is 66.7 years, but life expectancy varies a great deal between different countries. Human lifespan tends to correlate with economic development: people in the top 55 most developed nations have an average lifespan of 77.1 years, while people in the 33 least developed countries have an average lifespan of 49.4 years. In 2003, Japan had the highest life expectancy of 81.3 years, while Zambia had the lowest of 33.4 years (HD reports).

The rat's age in human years

Rat's age in months

Rat's age in years

Rat's age in human years

1.5 months (puberty)

0.125 years

12.5 years (puberty)

6 months (social maturity)

0.5 years

18 years (social maturity)

12 months

1 year

30 years

18 months

1.5 years

45 years

24 months

2 years

60 years

30 months

2.5 years

75 years

36 months

3 years

90 years

42 months

3.5 years

105 years

45 months

3.75 years

113 years

48 months

4 years

120 years

Note: This is a fun exercise and should not be taken too seriously!

All photographs, graphics, text and sounds on this website are Copyright © 2003, 2004.  All rights reserved.
Please request permission if you wish to use any images or content on this website
Contact: (where x = webmaster, y = ratbehavior)