How to Estimate Body Water Percentage (Watson Formula)
The Watson formula estimates total body water (TBW) in liters from age, height, and weight. For a 30-year-old man, 175 cm and 70 kg, TBW is about 42.0 L, or about 60.0% of body weight.
Open the interactive Everyday Lifestyle tool →Formula: TBW(men, L) = 2.447 - 0.09156 x age + 0.1074 x height(cm) + 0.3362 x weight(kg)
Key facts
| Formula | TBW(men, L) = 2.447 - 0.09156 x age + 0.1074 x height(cm) + 0.3362 x weight(kg) |
|---|---|
| Men, 30y/175cm/70kg | ~42.0 L (~60.0%) |
| Women, 28y/163cm/60kg | ~30.1 L (~50.2%) |
| Formula (women) | TBW = -2.097 + 0.1069 x height(cm) + 0.2466 x weight(kg) |
Frequently asked questions
What is total body water (TBW)?
The total volume of water in the body, typically 45-65% of body weight, estimated here with the Watson formula from age, height, and weight.
Why is the formula different for men and women?
Men and women have different average body composition (fat vs. lean mass ratio), so the Watson formula uses separate coefficients for each.
What is a typical body water percentage?
Roughly 50-65% of body weight for most adults, generally higher in leaner individuals since muscle holds more water than fat.
Related pages
The calculations on this page are estimates based on common general-purpose formulas. They are not medical advice -- consult a doctor or other qualified professional for decisions about your health.
Body Water Percentage Calculator is part of Everyday Lifestyle on GOAT Lab — a free reference you can use without signing up, and it works offline. Open the tool above for any custom value.
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