How long does a mouse grow? - briefly
A typical house mouse attains a body length of about 7–10 cm (2.8–4 in) within a few weeks after birth. Including the tail, the overall length reaches roughly 15–20 cm (6–8 in).
How long does a mouse grow? - in detail
Mice reach physical maturity within a relatively brief period compared to larger mammals. After birth, neonates weigh 1–2 g and are hairless, eyes closed, and incapable of thermoregulation. Growth proceeds through distinct phases:
- First week: Weight increases to 3–5 g; fur appears and eyes open. Milk intake remains the sole nutrient source.
- Second week: Rapid weight gain to 7–10 g; weaning begins as solid food is introduced.
- Third week: Weight reaches 12–15 g; locomotor coordination improves, and the mouse becomes fully independent.
- Fourth week: Adult size is approached, with weight stabilizing around 18–25 g for common laboratory strains (e.g., C57BL/6). Some wild species attain 30 g or more.
Full skeletal and reproductive maturity is typically achieved by 6–8 weeks of age. At this point, sexual cycles commence, and the animal can produce offspring. Environmental conditions, strain genetics, diet quality, and sex influence the exact timeline and final body mass. For instance, high‑protein diets can accelerate weight gain, while colder ambient temperatures may modestly retard growth.
In summary, a mouse progresses from birth to adult stature in roughly 30 days, with the most accelerated growth occurring between days 7 and 21. After reaching the adult weight range, growth plateaus, and subsequent weight changes reflect health status rather than continued somatic development.