Last verified 16 Sep 2026 · Sources
| Quick facts | Serving size rules |
|---|---|
| Regulation | 21 CFR 101.9(b) |
| Applies to | Any packaged food required to bear a Nutrition Facts label |
| Key numbers | Discrete units: ≤50% RACC → nearest whole-unit count; 67%–<200% → 1 unit. Single-serving: <200% of RACC = 1 serving. Servings 2–5 round to nearest 0.5. |
Answering the question
Serving size on a Nutrition Facts label isn’t a marketing choice. It’s a calculation set out in 21 CFR 101.9(b), starting from your product’s RACC (Reference Amount Customarily Consumed) under 21 CFR 101.12 and converting it into a household measure with a metric equivalent. The rule specifies exactly which units to use, in what order, how to count discrete units like cookies or crackers, when a whole package counts as one serving, and how to round the “servings per container” line. Get any one of those steps wrong and the %DV for every nutrient on the panel is calculated off a false base.
The rule
Start with the RACC for your product’s category (21 CFR 101.12). From there, 21 CFR 101.9(b) governs the conversion to a label serving size:
Discrete units (101.9(b)(2)(i)). For products sold as individual units (cookies, crackers, candies), the rule states: “If a unit weighs 50 percent or less of the reference amount, the serving size shall be the number of whole units that most closely approximates the reference amount,” and “if a unit weighs 67 percent or more, but less than 200 percent of the reference amount, the serving size shall be one unit.” Between 50% and 67%, you may declare 1 or 2 units, whichever more closely approximates the reference amount. Above 200%, an additional per-unit column applies alongside the package serving.
Household measures (101.9(b)(5)). The regulation directs that “cups, tablespoons, or teaspoons shall be used wherever possible and appropriate except for beverages,” for which fluid ounces are allowed. Cup measures must fall in 1/4- or 1/3-cup increments; tablespoon measures in 1, 1 1/3, 1 1/2, 1 2/3, 2, or 3 tbsp; teaspoon measures in 1/8, 1/4, 1/2, 3/4, 1, or 2 tsp. When none of those fit the product, “piece,” “slice,” “tray,” “jar,” and fractions of those are acceptable instead. Cup, then tablespoon, then teaspoon, then piece/slice, is the order the rule works through.
Single-serving containers (101.9(b)(6)). A product “packaged and sold individually that contains less than 200 percent of the applicable reference amount must be considered to be a single-serving container,” and the entire contents must be labeled as one serving.
Fluid ounces / mL (101.9(b)(7)). The declared serving size “shall be followed by the equivalent metric quantity in parenthesis (fluids in milliliters and all other foods in grams).”
Servings per container (101.9(b)(8)). The number of servings is “rounded to the nearest whole number except for the number of servings between 2 and 5 servings and random weight products,” which round instead “to the nearest 0.5 serving.”
The numbers
| Rule | Threshold | Result |
|---|---|---|
| Discrete unit (b)(2)(i) | Unit ≤50% of RACC | Whole-unit count closest to RACC |
| Discrete unit (b)(2)(i) | Unit >50% and <67% of RACC | Declare 1 or 2 units, closer approximation |
| Discrete unit (b)(2)(i) | Unit ≥67% and <200% of RACC | Serving = 1 unit |
| Single-serving (b)(6) | Package <200% of RACC | Entire contents = 1 serving |
| Servings per container (b)(8) | 2 to 5 servings | Round to nearest 0.5 |
| Servings per container (b)(8) | All other counts | Round to nearest whole number |
On the label
A bag of granola bars: each bar weighs 45 g, and the RACC for grain-based bars is 40 g. That’s 112% of the RACC, squarely in the “≥67% and <200%” band, so the serving size is 1 bar, declared as “1 bar (45 g)” per 101.9(b)(7). Now take a single-serve bag of chips sold individually at 42 g, with a snack-category RACC of 30 g. At 140% of the RACC, it’s still under 200%, so 101.9(b)(6) makes the whole bag one serving: “1 bag (42 g),” not a fractional serving based on the 30 g reference amount. A 12 fl oz can of soda, RACC 360 mL, states its serving size as “12 fl oz (355 mL),” using fluid ounces because it’s a beverage under 101.9(b)(5).
Mistakes we see
- Declaring a household measure that isn’t one of the specified increments (e.g., “2.5 tbsp” instead of stepping to the nearest allowed fraction).
- Treating a resealable multi-ounce bag as automatically multi-serving without checking the 200%-of-RACC single-serving threshold in 101.9(b)(6).
- Rounding “3.4 servings per container” down to “3” instead of to the nearest 0.5 as (b)(8) requires for containers between 2 and 5 servings.
- Skipping the metric equivalent in parentheses, which (b)(7) requires on every serving size line.
- Using ounces (weight) interchangeably with fluid ounces (volume) for beverages. They aren’t the same unit.
Related rules
Serving size starts with what is a RACC, the category reference amount this whole conversion is built from. Once serving size is locked in, rounding rules govern how each nutrient value is rounded for that serving, and dual-column when required covers the packages whose RACC-to-package ratio triggers a second per-container or per-RACC column.
Build it right the first time
Our serving-size wizard runs your product through 101.9(b) automatically (matching RACC, unit count, household measure, and servings-per-container rounding), so you don’t have to work the thresholds by hand.
A serving size set from the right RACC gives every %DV on your panel a true base to stand on. Enter your recipe, then see your label: your calories, the claims you qualify for and your allergen line are free, no card required, and every other value and %DV stays hidden until you unlock it. $29 unlocks every other nutrient value and %DV, every FDA format your product qualifies for, and your ingredient statement and allergen declaration, ready to print. Start your label or look up your category in what is a RACC.
FAQ
Can I round my serving size to a "nicer" household measure?
No. 101.9(b)(5) specifies the exact cup, tablespoon, and teaspoon increments allowed (like 1/4- or 1/3-cup steps), so the household measure has to land on one of those, not whatever reads cleanest on the panel.
Why does my single-serving snack still say "1 serving per container"?
Under 101.9(b)(6), any individually packaged, individually sold product containing less than 200% of the RACC must be labeled as one serving (the entire package), regardless of how it's later portioned.
Do beverages use cups or fluid ounces?
Cups, tablespoons, or teaspoons are used wherever possible except for beverages, where you may use fluid ounces per 101.9(b)(5) and (b)(7).
How do I round "servings per container" if my package has 3.2 servings?
Per 101.9(b)(8), servings between 2 and 5 round to the nearest 0.5 serving, so 3.2 becomes 3.
Related rules
What is a RACC?, Rounding rules, When is dual column required?. See the full all labeling rules.