# Free Water Calculation

Enteral formulas are composed of carbohydrates, fats, proteins, micronutrients, and free water. The majority of the formulation (60-85%) is free water and can be easily calculated.

**Example:**

- Formula A is 70% free water
- Total volume of formula prescribed is 1300 mL
- Estimated patient fluid needs = 1600 mL per day
- 1300 mL x 0.70 = 910 mL free water available to meet patient fluid needs
- 1600 mL – 910 mL = 690 mL additional free water needed to meet 100% estimated fluid needs