Total Body Water Calculator

Calculate TBW & Hydration Status

Calculate your total body water, intracellular and extracellular water distribution, and daily hydration needs.

Personal Information

kg
cm

About Total Body Water

Total body water (TBW) is the total amount of fluid in the human body. It makes up approximately 50-70% of body weight and is essential for all bodily functions.

Hydration Tips

  • Drink water throughout the day
  • Increase intake during exercise
  • Monitor urine color (pale yellow is ideal)
  • Eat water-rich foods (fruits, vegetables)
  • Adjust for climate and activity level

Understanding Body Water

Intracellular Water (ICW):

Water inside cells, about 67% of TBW. Essential for cellular functions.

Extracellular Water (ECW):

Water outside cells, about 33% of TBW. Includes blood plasma and interstitial fluid.

Factors Affecting TBW:

  • Age (decreases with age)
  • Gender (males typically higher)
  • Body composition (muscle vs fat)
  • Hydration status

Calculation Methods

Watson Formula:

Most accurate, considers age, height, and weight. Recommended for clinical use.

Hume-Weyers Formula:

Based on height and weight. Good alternative to Watson formula.

Simple Percentage:

Quick estimate using 60% for males, 55% for females. Less accurate but easy.

Clinical Applications:

  • Fluid management in hospitals
  • Dialysis treatment planning
  • Nutritional assessment
  • Sports medicine & hydration