kcal100

kcal100 is a label convention used in nutrition data to denote the energy content of a food item standardized to a fixed amount of mass, typically 100 grams or 100 milliliters. The value is expressed in kilocalories (kcal). By reporting energy per 100 g, kcal100 allows easy comparison of foods with different serving sizes and densities, supporting portion planning and dietary analysis.

Calculation of kcal100 is usually based on the Atwater system, which assigns average energy yields to macronutrients: fat provides about 9 kcal per gram, carbohydrate about 4 kcal per gram, and protein about 4 kcal per gram. Alcohol contributes about 7 kcal per gram. In practice, the reported kcal/100 g may reflect this calculation, with some jurisdictions applying specific rules for fiber or other components. The resulting kcal/100 g can be used to estimate total energy for any portion by multiplying the kcal/100 g by the portion mass (in grams) and dividing by 100.

Example: if a product contains 10 g fat, 20 g carbohydrate, and 5 g protein per 100 g, its energy is roughly 10×9 + 20×4 + 5×4 = 90 + 80 + 20 = 190 kcal per 100 g.

Limitations include rounding, moisture variation, cooking, and ingredient substitutions, all of which can affect the actual energy available. Different labeling regimes may also treat fibers and other components differently in energy calculations. kcal100 remains a practical standard for comparing energy density across foods and for nutrition planning.

See also: energy density, kilocalorie, nutrition labeling, Atwater factors.