Nutrition Label Portion Calculator
A label usually describes one serving—not automatically the quantity you ate. Copy the serving values and scale them to your actual portion.
Published by Reeve Editorial Team · Methods and sources updated
For 45 g
180 kcal
6 g protein · 27 g carbs · 6 g fat · 1.5 label servings
Inputs stay in this tab. Saving keeps a copy on this device until you reset or clear it.
Use the same unit for the label serving and amount eaten. Labels are rounded, so scaled results remain estimates.
How this tool works
The calculator divides the amount eaten by the label serving amount, then multiplies calories and each macro by that number of servings.
The serving amount and amount eaten must use the same unit. For example, compare grams with grams or pieces with pieces. If the label lists both a household measure and grams, grams usually provide the cleaner calculation when a scale is available.
Nutrition labels use permitted rounding conventions, and the contents of a real package can vary. The scaled result is therefore more appropriate as a logging estimate than an exact laboratory value.
Sources
Frequently asked questions
What if I ate the whole package?
Enter the total package amount in the amount-eaten field. If the package contains three equal label servings, the result will scale every nutrient by three.
Can I mix grams and milliliters?
Not without a food-specific density conversion. Use the same unit on both sides unless the package gives a reliable equivalent.
Why do the macro calories not exactly match the printed calories?
Labels round nutrient values, and calorie calculations can also reflect fiber, sugar alcohols, alcohol, and jurisdiction-specific conventions.