Nutrition Facts Label

The Nutrition Facts label is the standardised nutrition disclosure panel required by the U.S. Food and Drug Administration on nearly all packaged foods offered for retail sale. It is governed by 21 CFR 101.9, a regulation that runs to tens of thousands of words and specifies — with unusual precision for consumer-facing labelling — the serving size, the required nutrient list, the permitted calculation methods, the rounding rules, and the tolerance bands that determine when a label is non-compliant.

What the label is

The Nutrition Facts panel is not a measurement. It is a regulatory artefact: a structured summary of nutrient content, derived from either laboratory analysis of the product or from calculated values based on ingredient nutrient profiles, rounded to specified increments, and presented in a fixed visual template. The calorie number is calculated almost always using the general Atwater factors applied to measured or calculated macronutrient content. The FDA permits three calculation methods — Atwater general, Atwater specific, and direct calorimetry — but in practice the general factors dominate because they are the cheapest defensible path.

The 2016 revision

The last material revision to 21 CFR 101.9 was finalised in May 2016, with a compliance deadline of January 2020 for manufacturers with over $10 million in annual food sales (one year later for smaller manufacturers). The revision: enlarged the calorie typeface; split "total sugars" into "total" and "added"; dropped "calories from fat" as a required line; updated Daily Values in line with the 2015 Dietary Guidelines; and recalibrated serving sizes under the Reference Amounts Customarily Consumed (RACC) framework, with some categories (soda, ice cream) effectively doubling their listed serving to reflect typical consumption.

Tolerances

Label figures are subject to tolerance bands defined in 21 CFR 101.9(g). Class II nutrients — those naturally occurring in the food — are tolerated at 80 per cent of the label value on the low side, with no upper bound: a calorie figure of 200 kcal/serving is compliant if the analytically measured value is between 0 and roughly 240 kcal. Class I nutrients — those added or fortified — are held to tighter bounds (at least 100 per cent of label value, with an upper tolerance that depends on product category). Calories are typically Class II. This is the quantitative reason that a Nutrition Facts calorie figure cannot be treated as a precise measurement.

Rounding

All figures on the panel are rounded under rules specified in the regulation. Calories under 50 are rounded to the nearest 5; calories 50 and above, to the nearest 10. Protein, carbohydrate, and fat under 1 gram are expressed as "less than 1 g" or "not a significant source of"; above 1 g, they are rounded to the nearest gram. Sodium under 140 mg rounds to the nearest 5 mg. The cumulative effect of the rounding rules is that a label figure typically carries an inherent precision on the order of ±2.5 kcal for small-calorie items and ±5 kcal for larger ones, before any tolerance band is applied.

Implications for tracking accuracy

A consumer tracking app that ingests Nutrition Facts figures cannot be more accurate than the Nutrition Facts figures themselves. A label that says "240 calories per serving" carries an embedded ±5 kcal rounding band and an additional 20 per cent tolerance; a tracker that logs "240 kcal" for that serving is reporting the label, not the food. Research-grade dietary assessment handles this by sampling analytically rather than by reading labels; consumer assessment handles it by ignoring it.