How much does a common mouse weigh? - briefly
A typical house mouse weighs about 18–25 g (0.6–0.9 oz). This figure refers to the animal’s body mass alone, excluding any bedding or food.
How much does a common mouse weigh? - in detail
The typical house mouse (Mus musculus) weighs between 12 g and 30 g, with most adult individuals clustering around 18 g to 22 g. Laboratory strains, which are bred for consistency, usually fall in the 20 g–25 g range. Field mice (Apodemus sylvaticus) display a similar span, 15 g to 30 g, but tend toward the upper limit in nutrient‑rich environments.
Weight differences arise from several factors:
- Sex: males are on average 2 g–3 g heavier than females.
- Age: juveniles under four weeks weigh less than 5 g; full adult mass is reached by eight weeks.
- Seasonal food availability: individuals captured in autumn may weigh up to 5 g more than those in spring.
- Genetic line: inbred laboratory lines may exhibit narrower weight distribution than wild populations.
Measurement practices are standardized. Live specimens are placed in a calibrated analytical balance with a precision of 0.01 g. For ethical handling, mice are weighed briefly, then returned to their enclosure. Post‑mortem weighing includes removal of the gastrointestinal tract to obtain a “clean” body mass, a method used in comparative physiology studies.
Conversions for reference: 1 g ≈ 0.035 oz; thus a 20‑g mouse corresponds to roughly 0.7 oz. Compared with larger rodents, such as a Norway rat (Rattus norvegicus) at 250 g–300 g, the mouse represents roughly one‑tenth of the mass.
In research contexts, body mass is a key variable for dosing calculations, metabolic rate estimation, and behavioral assessment. Accurate weight records enable reproducibility across experiments and facilitate cross‑species scaling of physiological data.