Body Water Percentage Calculator
Estimate your body water percentage — the share of your weight made up of water — using the Watson total body water formula. Enter your sex, age, height, and weight to see your body water percentage and total body water in litres.
- Population estimate; daily hydration fluctuates.
Formula
Body water % = total body water (Watson) / weight × 100
- Body water percentage is total body water (from the Watson formula) divided by body weight, times 100.
- The Watson equations estimate total body water from sex, age, height, and weight.
- Typical ranges are about 50–65% for men and 45–60% for women.
- Leaner, more muscular bodies hold a higher water percentage because muscle is wetter than fat.
- Daily hydration, meals, and exercise shift the figure, so treat it as an estimate.
Man, 30, 175 cm, 75 kg
Inputs
- Gender: male
- Age: 30 years
- Height: 175 cm
- Weight: 75 kg
Watson TBW ≈ 43.5 L; dividing by 75 kg gives about 58% body water, within the typical male range.
Frequently asked questions
What is body water percentage?
It is the proportion of your body weight made up of water, both inside and outside your cells.
What is a healthy body water percentage?
Roughly 50–65% for men and 45–60% for women, depending on age, body fat, and hydration.
Why do men have higher body water?
Men typically carry more muscle and less fat, and muscle holds far more water than fat tissue.
Does body water change during the day?
Yes. Drinking, eating, sweating, and exercise all move the number up or down within a normal range.
How accurate is this estimate?
The Watson formula is a solid population estimate but cannot match direct measurement like bioimpedance or dilution methods.
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