How much does a domestic rat weigh? - briefly
A typical pet rat weighs between 300 g and 500 g, with most adult individuals averaging around 350–400 g.
How much does a domestic rat weigh? - in detail
Domestic rats kept as pets typically weigh between 300 and 500 grams when fully mature. Males are generally heavier than females, with adult males averaging 350–500 g and adult females averaging 300–400 g. Weight varies with strain; standard “fancy” rats often fall in the lower part of the range, while larger “giant” strains can exceed 600 g.
Growth follows a predictable pattern. Newborn pups weigh 5–7 g. By three weeks, they reach 50–80 g. At eight weeks, most individuals are 150–250 g, and full adult size is achieved around four to five months.
Factors influencing body mass include:
- Genetics: Strain and lineage determine maximum size potential.
- Sex: Males develop more muscle mass and a larger skull.
- Diet: High‑protein, balanced feed promotes healthy growth; excessive treats can cause obesity.
- Health status: Parasites, infections, or chronic disease may lead to weight loss.
- Environment: Temperature and cage size affect activity levels, which in turn impact weight.
Accurate measurement requires a digital kitchen scale with a capacity of at least 1 kg and a precision of 1 g. Weigh the animal in a small container to prevent movement; record the weight at the same time of day to reduce variability caused by recent feeding.
Monitoring weight regularly helps detect early signs of illness. A sudden change of more than 10 % of body mass within a week warrants veterinary assessment. Maintaining the species‑specific weight range supports optimal health, longevity, and reproductive performance.