Body Water Percentage Calculator Formula
Understand the math behind the body water percentage calculator. Each variable explained with a worked example.
Formulas Used
Total Body Water
tbw_liters = 2.447 - 0.09156 * age + 0.1074 * height_cm + 0.3362 * weight_kgBody Water Percentage
tbw_pct = (2.447 - 0.09156 * age + 0.1074 * height_cm + 0.3362 * weight_kg) / weight_kg * 100Total Body Water
tbw_gallons = (2.447 - 0.09156 * age + 0.1074 * height_cm + 0.3362 * weight_kg) * 0.264172Variables
| Variable | Description | Default |
|---|---|---|
weight_lbs | Body Weight(lbs) | 180 |
height_inches | Height(inches) | 70 |
age | Age(years) | 30 |
weight_kg | Derived value= weight_lbs * 0.453592 | calculated |
height_cm | Derived value= height_inches * 2.54 | calculated |
How It Works
Watson Formula for Total Body Water (Male)
TBW (L) = 2.447 - 0.09156 x Age + 0.1074 x Height(cm) + 0.3362 x Weight(kg)
The Watson formula is widely used in clinical settings to estimate total body water.
Healthy Body Water Ranges
Worked Example
A 30-year-old male, 180 lbs, 70 inches.
- 01Weight = 81.6 kg, Height = 177.8 cm
- 02TBW = 2.447 - 0.09156 x 30 + 0.1074 x 177.8 + 0.3362 x 81.6
- 03= 2.447 - 2.747 + 19.1 + 27.4 = 46.2 liters
- 04Body water % = 46.2 / 81.6 x 100 = 56.6%
Frequently Asked Questions
What percentage of the body is water?
Adult males are typically 50-65% water. Muscle tissue contains about 75% water while fat tissue contains about 10%, so leaner individuals have higher body water percentages.
What is the Watson formula?
The Watson formula (1980) estimates total body water from age, height, and weight. It is commonly used in medicine for drug dosing and fluid balance calculations.
How can I stay well hydrated?
Drink water throughout the day, eat water-rich foods, monitor urine color (pale yellow is ideal), and increase intake during exercise or hot weather.
Ready to run the numbers?
Open Body Water Percentage Calculator