The formula to calculate the Hydration Index (HI) is:
\[ HI = \frac{WU}{BW} \]
Where:
A Hydration Index is a measure used to determine how well a beverage hydrates the body compared to a standard reference, usually water. It takes into account factors such as the volume of fluid intake, the drink’s nutrient composition, and the body’s fluid balance over a certain period after consumption. This index is useful in understanding the hydration effectiveness of different beverages, which can aid in maintaining optimal hydration levels for health and performance.