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📘 About the Body Water %
Water makes up the largest part of your body: about 50–65% of an adult man's weight and 45–60% of an adult woman's. Total body water (TBW) is the water in all your cells, blood and other fluids.
This calculator uses the Watson formula with your age, sex, height and weight to estimate total body water in litres and your body water percentage, then compares it with the typical healthy range.
Muscle is about 75% water while fat is only about 10–20% water, so people with more muscle have a higher body water percentage.
🧮 Formula
✏️ Worked examples
Man, 30 years, 175 cm, 75 kg
You get| Total body water | 43.7 litres |
| Body water percentage | 58.3% |
| Typical range for adult men | 50–65% |
| Your result | Within the typical healthy range |
| Daily water guide (about 35 ml per kg) | 2.6 litres a day from food and drinks |
Total body water 43.7 litres; body water 58.3%.
Try this example →Woman, 35 years, 160 cm, 60 kg
You get| Total body water | 29.8 litres |
| Body water percentage | 49.7% |
| Typical range for adult women | 45–60% |
| Your result | Within the typical healthy range |
| Daily water guide (about 35 ml per kg) | 2.1 litres a day from food and drinks |
Total body water 29.8 litres; body water 49.7%.
Try this example →🧭 How to use this calculator
What you enter
- Gender
- Age (yrs)
- Height (cm)
- Weight (kg)
What you get
- Total Body Water
- As % of Body Weight
💡 Body water percentage chart
- Newborn babies: 75–78%
- Children: 60–65%
- Adult men: 50–65%
- Adult women: 45–60%
- Adults over 60: 45–55%
❓ Frequently asked questions
What is a healthy body water percentage?
About 50–65% for adult men and 45–60% for adult women. It falls a little with age.
What percentage of the human body is water?
About 60% on average for adults — higher in infants (about 75%) and lower in older adults and people with more body fat.
How much body water should I have?
A 70 kg man typically has about 40–42 litres; a 60 kg woman about 30 litres. The calculator gives your estimate in litres.
Does it show hydration?
No. It estimates the normal amount of water for your body size, not whether you are dehydrated today.
Why does it fall with age?
Muscle mass, which holds a lot of water, tends to fall with age while fat mass rises.
How can I increase my body water percentage?
Building muscle and reducing body fat raise it over time. Drinking water keeps you hydrated but does not permanently change the percentage.
