Skin
Skin
The largest organ — about 2 m² and 4 kg in an adult.
Provides a barrier against pathogens and water loss, regulates temperature through sweat and blood flow, synthesises vitamin D, and carries the sense of touch, pressure, temperature and pain.
Where it is
The entire external surface.
The numbers
- Area
- 1.5–2.0 m²
- Mass
- about 4 kg, or 16% with fat
- Thickness
- 0.5 mm on eyelids to 4 mm on soles
- Full renewal
- about 4 weeks
Worth knowing
The outermost layer is entirely dead cells, replaced roughly every four weeks, and a substantial fraction of household dust is shed skin. Skin colour comes from melanin produced by melanocytes, and everyone has approximately the same number of melanocytes — what differs is how much melanin they produce.
Structural reference only — this is not medical advice, and individual variation in every figure here is substantial. Anything concerning your own health belongs with a clinician rather than a reference page.
Common questions
- What does the skin do?
- Provides a barrier against pathogens and water loss, regulates temperature through sweat and blood flow, synthesises vitamin D, and carries the sense of touch, pressure, temperature and pain..
- Skin — key numbers
- Area: 1.5–2.0 m². Mass: about 4 kg, or 16% with fat. Thickness: 0.5 mm on eyelids to 4 mm on soles. Full renewal: about 4 weeks.
Related pages
- Heart A four-chambered pump, roughly fist-sized, beating about 100,000 times a day.
- Brain About 1.4 kg, using roughly 20% of the body’s energy at 2% of its mass.
- Liver The largest internal organ, around 1.5 kg, and the only one that regenerates.
- Lungs Two unequal lungs with a gas-exchange surface of about 70 square metres.
- Kidneys Two fist-sized filters processing about 180 litres of blood a day.
- Bones Bones
- Blood types Blood
- Teeth Teeth
- Blood Blood
- The senses Senses
- Taste Senses
Sources
- Typical range compiled from manufacturer specifications — At One Place