How much does a pet rat weigh? - briefly
A typical domesticated rat weighs between 250 g and 500 g (approximately 0.55–1.1 lb), with females generally lighter than males. Weight varies by breed, age, and diet.
How much does a pet rat weigh? - in detail
Pet rats typically fall within a predictable weight spectrum that reflects age, sex, and strain. Newborn pups weigh approximately 5–7 g (0.18–0.25 oz). By three weeks, they reach 30–40 g (1.1–1.4 oz). Full‑grown adults usually measure between 250 and 500 g (8.8–17.6 oz).
- Standard fancy rats: 300–350 g (10.6–12.3 oz) for females, 350–400 g (12.3–14.1 oz) for males.
- Dwarf varieties (e.g., Dumbo, hairless): 150–250 g (5.3–8.8 oz), with females generally lighter than males.
- Large‑breed fancy rats (selected for size): up to 500 g (17.6 oz).
Weight progression follows a rapid increase during the first month, then slows to a steady gain of 5–10 g (0.18–0.35 oz) per week until maturity. Factors influencing final mass include:
- Dietary composition – high‑protein, balanced pellets maintain optimal growth; excessive fat or treats can cause overweight conditions.
- Health status – parasites, respiratory infections, or metabolic disorders may reduce or inflate body weight.
- Genetic line – selective breeding for size or dwarfism directly alters average mass.
Regular weighing with a digital scale accurate to 0.1 g provides the most reliable monitoring. Deviations of more than 10 % from the expected range for a given age and strain warrant veterinary evaluation.