Humans are made of roughly 50–75% water , with an average adult sitting around 60% water by body weight. The exact percentage varies with age, sex, and body composition, so “how much water” you are depends on who you are.

Quick Scoop

  • Most adults: about 50–60% water by weight.
  • Typical “sound‑bite” fact: people often say “about 60–70% water,” which is roughly true for many healthy adults.
  • Range across life: from about 75–78% in newborns down to around 45–50% in some older adults.

Does it change by age and sex?

Yes, a lot.

  • Infants and children : around 60–78% water , with newborns at the upper end (about three‑quarters water).
  • Adult men : commonly average about 59–60% water , though values roughly 43–73% are seen depending on body fat and muscle.
  • Adult women : often average about 50–56% water , with a typical range from the low 40s up to low 60s because higher body fat means less water.

Which body parts are most water?

Some parts of you are much more watery than others.

  • High‑water organs: the brain and heart are about 73% water , lungs about 83% , muscles and kidneys around 79% , and skin in the mid‑60–70% range.
  • Lower‑water parts: bones are around 31% water , and teeth are even lower because they are mostly mineral.

Example organ water percentages (approx.)

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Body part Approx. water content
Brain ≈ 73% water
Heart ≈ 73% water
Lungs ≈ 83% water
Muscles / kidneys ≈ 79% water
Skin ≈ mid‑60–70% water
Bones ≈ 31% water

Why the percentage isn’t the same for everyone

Several factors shift your personal “water percentage” up or down.

  • Body fat vs. muscle : muscle tissue holds a lot of water, while fat tissue holds much less, so more muscle usually means a higher body‑water percentage.
  • Ageing : as people age, they often lose muscle and gain fat, so total body water can drop into the mid‑40% range.

Why all that water matters

Water is not just “filler”; it is doing constant work in the background.

  • It acts as the main medium for chemical reactions , helps regulate temperature through sweating, and transports nutrients and waste in blood and other fluids.
  • Every cell contains water, so even relatively small losses (dehydration) can affect energy, thinking, and circulation.

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Humans are made of about 50–75% water, averaging around 60% in adults, with higher levels in infants and lower levels in older adults. Learn how age, sex, and body composition change your body’s water percentage and why it matters for health.

Information gathered from public forums or data available on the internet and portrayed here.