How much does a lab mouse weigh? - briefly
A typical laboratory mouse weighs between 20 and 30 grams, varying with strain, age, and sex. Adult females generally occupy the lower end of this range, while males tend toward the upper limit.
How much does a lab mouse weigh? - in detail
A laboratory mouse typically weighs between 15 g and 35 g, depending on strain, sex, age, and nutritional status.
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Strain differences:
- C57BL/6: 20–25 g for adult females, 22–28 g for adult males.
- BALB/c: 18–22 g for females, 20–26 g for males.
- Swiss Webster outbred: 22–30 g for females, 25–35 g for males.
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Age factor:
- Neonates (0–7 days) weigh 1–2 g.
- Juveniles (3–4 weeks) reach 8–12 g.
- Adults (8–12 weeks) attain the ranges listed above.
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Sex influence: Males are consistently 10–15 % heavier than females of the same strain and age.
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Diet and health: Caloric restriction or disease can reduce body mass by 5–20 %, while overfeeding may increase it by a similar margin.
Weight is measured with analytical balances that resolve 0.01 g, calibrated regularly to ensure accuracy. In experimental protocols, body mass is recorded weekly to monitor growth curves, assess welfare, and adjust drug dosing, which is commonly calculated as mg kg⁻¹. For reference, a mouse weighing 25 g corresponds to 0.025 kg, so a dose of 10 mg kg⁻¹ translates to 0.25 mg per animal.
Standard deviations in weight measurements for a homogeneous cohort typically fall between 0.5 g and 1.5 g, reflecting natural biological variability. Reporting should include mean weight, standard deviation, and the number of subjects (n) to permit reproducibility and proper statistical analysis.
Overall, precise knowledge of mouse mass is essential for experimental design, humane care, and reliable interpretation of pharmacological or physiological data.