Calculating your total body water (TBW) provides insight into your overall hydration. While several methods exist, a common approach uses the Watson formula, which takes into account age, height, and weight.
Using the Watson Formula
The most frequently cited formula for estimating TBW is the Watson formula. Different variations exist, but a common one is:
For males: 2.447 – (0.09156 x age) + (0.1074 x height in centimeters) + (0.3362 x weight in kilograms) = total body water (TBW) in liters
This formula provides an estimate. Other formulas may exist for females, but the provided references primarily focus on this male-specific variation. The slight discrepancies in coefficients across sources are likely due to rounding or variations in the original research.
Example:
Let's say a male is 35 years old, 180 centimeters tall, and weighs 80 kilograms. The calculation would be:
2.447 – (0.09156 x 35) + (0.1074 x 180) + (0.3362 x 80) = 42.87 liters (approximately)
Therefore, his estimated TBW is approximately 42.87 liters.
Calculating Body Water Percentage
To determine the percentage of your body that is water, simply divide your TBW (in liters) by your weight (in kilograms) and multiply by 100. Remember that 1 liter of water roughly equals 1 kilogram.
Using the above example:
(42.87 liters / 80 kilograms) x 100 = 53.6%
This means approximately 53.6% of this individual's body weight is water.
Important Considerations
- These formulas provide estimates. Individual variations exist.
- The accuracy of these calculations depends on the accuracy of the input values (age, height, weight).
- For precise TBW measurement, more sophisticated methods like bioelectrical impedance analysis (BIA) are used.
