Total Body Water Calculator
Estimate your total body water from height, weight and age.
How much of you is water
A large share of the human body is water, and total body water can be estimated from height, weight, age and sex using established formulas. This gives that estimate, a figure of interest for understanding body composition and hydration.
Enter your details to estimate total body water.
A rough figure, and what it reflects
Total body water estimates are approximations from population formulas, and the real proportion varies between individuals — it tends to be higher in people with more muscle, since muscle holds more water than fat, and it shifts with age and sex. So the figure is a general reference rather than a precise measurement. It relates to body composition and gives a sense of how much of your mass is water, but everyday hydration is better judged by thirst and other simple signs than by a calculated total. This is general information, not medical advice; if you have a health condition affecting fluid balance, follow your healthcare professional's guidance.
Total Body Water Calculator FAQ
What affects total body water?
Body composition, age and sex — it tends to be higher in people with more muscle, since muscle holds more water than fat.
Is the estimate precise?
No — it is a population-based approximation that varies between individuals, so treat it as a general reference rather than a measurement.
Is this medical advice?
No — it is general information. If a health condition affects your fluid balance, follow your healthcare professional's guidance.