1. What is a Total Body Water Calculator by Age?

Definition: This calculator estimates the total body water volume based on body weight and an age-specific factor.

Purpose: It helps healthcare professionals and individuals estimate body water content for hydration assessment and medical calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( TBW \) — Total body water (liters)
• \( W \) — Body weight (kilograms)
• \( k_a \) — Age-specific factor (dimensionless, typically ~0.6 for adults)

Explanation: The body weight is multiplied by an age-specific constant that represents the proportion of body weight that is water.

3. Importance of Total Body Water Calculation

Details: Knowing total body water helps in assessing hydration status, calculating drug dosages, and managing fluid balance in medical conditions.

4. Using the Calculator

Tips: Enter your body weight in kilograms and the appropriate age factor (default 0.6 for adults). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical age factors (k_a)?
A: Newborns: ~0.75, Children: ~0.65, Adult males: ~0.6, Adult females: ~0.55, Elderly: ~0.5.

Q2: Why does the age factor vary?
A: Body water percentage decreases with age and varies by sex due to differences in body composition.

Q3: How accurate is this calculation?
A: It provides an estimate. For precise measurements, specialized tests like bioimpedance analysis are needed.

Q4: Can I use pounds instead of kilograms?
A: First convert pounds to kg (1 kg = 2.2 lbs) for accurate results.

Q5: What affects total body water besides age?
A: Body fat percentage, sex, fitness level, and health conditions can all influence TBW.