To measure the percentage of water in the body, CalCon has designed a Total Body Water calculator, which you can use as an Android or IOS application. Using CalCon Total Body Water Calculator, it is very simple to find the total body water amount. All you need to enter is age, height, body weight, and gender. The preferred measurement system can be metric or imperial.

CalCon Calculator is used to calculate the total amount of water in your body based on your age, height, weight, and gender. The calculation is based on a formula developed by Dr. P.E. Watson and his team, described in the article “Total body water volume for adult men and women estimated based on simple anthropometric measurements.

What is total body water?

Water is a component of all living beings and an indispensable ingredient of food. Water is vital for the normal functioning of the human body – it participates in all biochemical reactions in the human body and protects body parts from shocks. It makes up about 60-70% of an adult’s body weight and slightly more in children. It is, therefore, necessary for life and health.

Body water is defined as the water content of tissues, blood, bones, and other human body parts. All percentages of body water are added to total body water (TBW). Ensuring that this value remains constant and within healthy limits is part of a process of maintaining a biological system called homeostasis. Water is stored in two main sections of the body:

  • Intracellular fluid (ICF): intracellular fluid covers 2/3 of TBW;
  • Extracellular fluid (ECF): fluid outside the cells covers the remaining 1/3 of TBW.

Body water has several vital roles, such as being an essential nutrient, speeding up metabolism and transporting proteins and carbohydrates, forming a necessary part of temperature regulation, being a means of removing waste through urine, protecting the brain and spine as part of the fluid and being part of amniotic fluid in pregnancy.

The most commonly used rough estimate of body water is based on the rule that the average human body of an adult consists of approximately 60% water to deduct TBW over a person’s body weight.

However, several studies have devised different gender-specific equations that allow estimates of TBW based on more specific data, such as age and height.

Why is the total body water calculated by height, body weight, age, and sex?

A rough calculation of the total body water volume can be obtained, assuming that the average male adult consists of approximately 60-70% water and the average female adult about 50% water. However, if we consider several other advanced methods, the formula developed by Dr. P.E. Watson gives the best results. Dr. P.E. Watson’s calculation is based on body weight, height, age, and gender. In addition to the most commonly used Watson formula, some other formulas can be used, such as the Hume-Weyers formula or a specially designed formula for calculating TBW in children, according to the author Mellits-Cheek.

Total body water calculation formula

The CalCon Total Body Water calculator offers the calculation of the percentage of the total water content in the body based on P.E. Watson’s formula a which is given below:

MaleTBW = 2.447 - (0.09156 \times Age) + (0.1074 \times Height) + (0.3362 \times Weight)

FemaleTBW = 2.097 + (0.1069 \times Height) + (0.2466 \times Weight)

Where: Water is in liters, Age in years, Height in cm, Weight in kg.

To get the percentage of water in the body, assume that 1 liter = 1 kilogram. Then divide your total body weight or TBW by your weight. This gives you an overview of whether you are in a healthy percentage range or not.

Total body water calculation – an example

Based on the above formulas, let’s do one example of calculation using the CalCon Total Body Water calculator. Suppose we do a calculation for a male person who is 25 years old, is 189 cm tall, and weighs 105 kg. Then, the calculated TBW is 55.76 liters, representing the same amount in kilograms and the percentage of body weight is 53%.

total body water calcon calculator
Print screen from CalCon Total Body Water calculator

Total body water chart

During the first few months of life, almost three-quarters of body weight is water. However, that percentage starts to drop before you complete your first birthday.

The decrease in the percentage of water over the years is mainly due to higher body fat and less non-fat tissue as a person ages. Fat tissue contains less water than non-fat tissue, so your weight and body composition affect the percentage of water in your body.

The following table represents the average total amount of water in your body as an average percentage of body water and the ideal range for good health.

Adults12-18 years 12-18 years 19-50 year 19-50 year More than 51 years More than 51 years
AverageRange Average Range Average Range
Female59% 49-63%50%41-60%47%39-57%
Total Body Water: average and range as the function of age

Check our Adjusted Body Weight Calculator.


How much of our total body weight is water?

Most of the human body is water, with an average of about 60%. The amount of water in the body changes slightly with age, gender, and personal hydration levels. The average percentage of water in a person’s body is about 60%, and this rate can vary from about 45-75%.

How to calculate total body water from weight?

Total body water can be estimated based on premorbid (or ideal) body weight and correction factor if we use the following formula:

TBW = Weight \times C

C is the coefficient for the expected percentage of free water weight and varies from 0.45 to 0.6.

What is an ideal total body water percentage?

Water in the body drops as you age but will stay above 50 percent most, if not a lifetime. The normal range for adult women is between 45% and 60%. For men, the ideal percentage of water in the body varies between 50% and 65% of the total body. In babies, that number is much higher. The norm is between 75% and 78%, and by one year of age, it drops to 65%.

How to reduce total body water?

There is a number of ways a person can lose weight quickly and naturally. Some of the most effective treatments are:
• Reduce salt intake
• Consume plenty of water
• Reduce carbohydrate intake
• Use of supplements
• Activity and training
• Water regulation by pills

Why does total body water decreases with age?

The amount of water in the body decreases by approximately 15% (about 6 liters) between 20 and 80. With this reduction, the body becomes more susceptible to dehydration due to losing a small amount of body water. Moreover, the elderly often have a reduced feeling of thirst, which leads to reduced fluid consumption. Also, the kidneys have a reduced ability to concentrate urine and retain water during water shortages due to aging. Aging kidneys are less able to store or excrete sodium.
The decrease in the percentage of water over the years is also primarily due to higher body fat and less non-fat tissue as a person ages.