On this page
What body water percentage is
Body water percentage is the share of your total body weight made up of water. In a typical adult it's around 50–65%, and it's involved in nearly everything your body does — transporting nutrients, cushioning joints, regulating temperature and powering every cell.
Because water is so fundamental, your body-water level is a useful window into both hydration and body composition.
How it's calculated
This calculator uses the Watson formula, a clinically validated equation that estimates total body water (in litres) from your age, sex, height and weight. We then divide that by your weight to give a percentage. Healthy reference ranges are roughly 50–65% for men and 45–60% for women — women average a little lower because they carry more essential body fat, which holds less water than muscle.
What changes your body water
- Body fat. Fat tissue holds little water, so a higher body-fat percentage lowers your body-water percentage.
- Muscle. Muscle is about 75% water, so more lean mass raises it.
- Age. Body water tends to fall gradually with age as muscle is lost.
- Hydration. Day-to-day fluid intake causes small short-term swings.
Staying in a healthy range
Two things keep your body water where it should be: good day-to-day hydration and a healthy body composition. Drink to thirst (our water intake calculator gives a personalised target), build muscle through resistance training, and keep body fat in a healthy band — check yours with the body fat calculator.
Helpful tools
Track body water, fat and muscle trends at home.
View options →Stay consistently hydrated through the day.
View options →Some links may be affiliate links; if you buy through them we may earn a small commission at no extra cost to you.
Frequently asked questions
What's a healthy body water percentage?
Roughly 50–65% for men and 45–60% for women. Women average slightly lower because they carry more essential fat, which holds less water than muscle.
Why is my body water percentage low?
Most often because of a higher body-fat percentage rather than dehydration, since fat tissue holds little water. Building muscle and lowering body fat raises it.
Does drinking more water increase the percentage?
Only slightly and temporarily. Your body tightly regulates fluid balance, so long-term body-water percentage is driven mainly by body composition.
Why do men and women differ?
Women naturally carry more essential body fat, and fat contains less water than lean tissue, so their average body-water percentage sits a little lower than men's.