Body Water Calculation

Category: Vital Signs & Health Indicators
- April 12, 2025
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Estimate your total body water (TBW) and water distribution

cm
kg

Advanced Options (optional)

Total Body Water (TBW)
0.0 L
0%

Water Distribution

Intracellular Water (ICW)
0.0 L
0%
Water within cells
Extracellular Water (ECW)
0.0 L
0%
Water outside cells (blood, lymph)

About Body Water

Total body water (TBW) is the amount of water contained in your body, typically around 60% of total body weight in adult males and 55% in adult females.

Water is essential for numerous bodily functions including:

  • Regulating body temperature
  • Transporting nutrients and oxygen
  • Removing waste products
  • Cushioning joints and organs
  • Maintaining proper cell function

Body water is distributed in two main compartments:

  • Intracellular Water (ICW): Water inside your cells (about 2/3 of TBW)
  • Extracellular Water (ECW): Water outside your cells, including blood plasma and interstitial fluid (about 1/3 of TBW)

Calculation Methods

This calculator uses the Watson formula, one of the most widely accepted methods for estimating total body water.

Watson Formula for Males:

TBW (L) = 2.447 - (0.09516 × Age) + (0.1074 × Height) + (0.3362 × Weight)

Watson Formula for Females:

TBW (L) = -2.097 + (0.1069 × Height) + (0.2466 × Weight)

Where height is in cm and weight is in kg.

Body Water Percentage:

Water % = (TBW / Weight) × 100

When body fat percentage is known, a more accurate estimate can be made using the fact that fat-free mass contains approximately 73% water:

TBW based on Body Fat (alternative method):

Fat-Free Mass (kg) = Weight × (1 - (Body Fat % / 100))

TBW (L) = Fat-Free Mass × 0.73

Normal Body Water Ranges

Group TBW (% of body weight)
Adult Males 55-65%
Adult Females 45-55%
Athletes 60-70%
Elderly 45-55%
Infants 70-80%

Factors Affecting Body Water:

  • Age: Body water percentage decreases with age
  • Gender: Males typically have higher water percentage than females
  • Body Composition: Muscle tissue contains more water (75%) than fat tissue (10-20%)
  • Hydration Status: Dehydration decreases total body water

Splash Into the Numbers: Why a Body Water Calculator Just Makes Sense

The Body Water Calculator helps you figure out how much water is inside your body. That may sound kind of weird at first, but it's actually super useful. Our bodies are made up of a lot of water—more than half, in fact! This tool uses a few things like your age, height, weight, and gender to give you a good estimate of your total body water (also called TBW for short).

You can also learn how that water is split between two types: inside your cells (intracellular) and outside your cells (extracellular). That’s important for understanding how your body stays balanced, especially if you’re into sports, working on your health, or just curious.

Crunching the Core Functions

Here’s what this calculator can do:

  • 🧮 Estimate your Total Body Water (TBW) in liters
  • 📊 Show how much water is inside your cells (ICW)
  • 🧫 Show how much water is outside your cells (ECW)
  • 💧 Display what percentage of your body is made of water
  • 🔁 Switch between metric and imperial units
  • ⚙️ Add extra info like body fat percentage for more accurate results
  • 📉 Even shows a chart of your body water breakdown!

Water + Math = Everyday Wins

This calculator isn’t just for fun facts—it’s actually super helpful in everyday life:

  • Science class just got easier: If you’re learning about the human body, this can help you understand how water works in real life, not just on paper.
  • Stay on track with fitness goals: Knowing how much water is in your body can help you keep hydrated, especially if you work out a lot.
  • Plan smarter diets: If you’re watching your health, this gives you more than just numbers on a scale—it shows what’s going on inside.
  • Simple checks: Maybe you’re just curious if you’re drinking enough water or if your recent habits are making a difference.

Example: Let’s say you’re 25, 5'8", and 150 lbs. You pop those numbers in, and boom—you see how much of that 150 pounds is water. Super cool, and way easier than guessing.

Click, Type, Splash: How to Use It

Using the Body Water Calculator is as easy as drinking a glass of water. Just follow these steps:

  1. Pick your unit system: Metric (cm/kg) or Imperial (in/lb)
  2. Choose your gender
  3. Enter your age
  4. Type in your height and weight
  5. (Optional) If you know your body fat percentage, add that too
  6. Hit the “Calculate Body Water” button
  7. Check out your results and chart!

Want to start fresh? Just click the “Reset” button and it’ll clear everything out for you.

The Final Equation

Knowing how much water is in your body doesn’t have to be a guessing game. With the Body Water Calculator, it’s like having a smart friend who loves numbers and health facts. You don’t need to be a scientist or nutritionist. All it takes is a few clicks and a couple numbers.

Whether you're working on a school project, tracking your fitness, or just curious about your health, this tool helps you understand your body a little better. And let’s be honest—when it comes to our health, more info is always a win.

So go ahead. Crunch the numbers, splash into your stats, and see how much of you is water. 💦