Enter the body weight and the amount of extra water needed due to exercise or hot weather into the calculator to determine the amount of free water needed per day. This calculator can also evaluate any of the variables given the others are known.

Free Water Formula

The following formula is used to calculate the amount of free water needed per day.

FW = (BW * 0.033) + (E * 0.001)

Variables:

  • FW is the amount of free water needed per day in liters
  • BW is the body weight in kilograms
  • E is the amount of extra water needed due to exercise or hot weather, in minutes of exercise or degrees above 20°C

To calculate the amount of free water needed per day, multiply the body weight by 0.033 to get the base amount of water needed. Then, for every minute of exercise or degree above 20°C, add 0.001 liters to the base amount. The sum of these two calculations gives the total amount of free water needed per day.

What is Free Water?

Free water refers to the water that is not bound in a substance and can be removed through processes like drying or heating. It is the water that exists in a liquid state in a system and can be separated from the system without changing the properties of the substances in the system. It is often found in food products, soil, and other natural materials, and its presence can affect the texture, shelf life, and other characteristics of these materials.

How to Calculate Free Water?

The following steps outline how to calculate the Free Water using the given formula:


  1. First, determine the body weight (BW) in kilograms.
  2. Next, determine the amount of extra water needed due to exercise or hot weather (E) in minutes of exercise or degrees above 20°C.
  3. Next, insert the values of BW and E into the formula: FW = (BW * 0.033) + (E * 0.001).
  4. Finally, calculate the Free Water (FW).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Body weight (BW) = 70 kg

Extra water needed (E) = 30 minutes of exercise