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Fact Sheet on Metric Labeling for Consumer Packages

Why is Metric Labeling Now Required on Consumer Packages?

FPLA -- In 1966, Congress enacted the Fair Packaging and Labeling Act (FPLA) (15 U.S.C. 1451 et seq.), which established package labeling requirements to help consumers get accurate information on the net quantity of the contents of packages and make value comparisons between packages of similar commodities.

Metric Amendments to FPLA -- The Congress amended the FPLA on January 28, 1992, to require the use of the metric system on certain consumer packages in conformance with their overall policy that the metric system is the preferred system of weights and measures for commerce in the United States (Omnibus Trade and Competitiveness Act, Public Law 100-418, 15 U.S.C. 205b).

Metric Amendments to Model State Laws -- To ensure consistency with Federal labeling requirements, the National Conference on Weights and Measures (NCWM) revised the uniform weights and measures laws and regulations it develops for adoption by State and local governments to require use of the metric system on some consumer product labels.

Who is Responsible for Regulating Requirements for Metric Labeling?

For Consumer Products that are Foods, Drugs, or Cosmetics: Authority to promulgate regulations under the FPLA for any consumer commodity that is a food, drug, device, or cosmetic was assigned to the Secretary of now the Department of Health and Human Services (HHS). The agency within HHS that develops the regulations is the Food and Drug Administration (FDA). The FDA is in the process of amending its regulations to reflect the changes made to the FPLA.

For Some Nonfood Consumer Products Other than Foods, Drugs, and Cosmetics: Authority to promulgate regulations under the FPLA for certain other consumer products was assigned to the Federal Trade Commission (FTC). The FTC has amended its regulations issued under section 4 of the FPLA (16 CFR Part 500) to require both inch-pound and metric units on consumer packages; a final rule was published in the Federal Register on Wednesday, January 12, 1994.

For Other Consumer Products: For consumer packages not covered by Federal Government regulations, State and local government regulations apply. (State and local governments also share concurrent jurisdiction with Federal Agencies in the case of consumer packages covered by Federal regulations.) The NCWM develops uniform regulations for adoption by State and local governments. In July 1993, the NCWM adopted revisions to its Uniform Weights and Measures Law and Uniform Packaging and Labeling and Method of Sale Regulations to bring them into conformance with the FPLA and the Federal Regulations issued under the FPLA.

For Imported Products: In the case of any imports into the United States of consumer products covered by the FPLA, the provisions of the Act are enforced by the Secretary of the Treasury.

What Are the New Requirements?

Put Inch-Pound and Metric Units on Labels -- As a result of the changes to Federal and State regulations, both metric and inch-pound units must be included in the quantity declaration on the principal display panel (PDP) of consumer packages (with the exceptions noted below). (Consumer packages, as defined by the NCWM, are those that are customarily produced or distributed for sale through retail sales agencies or instrumentalities for consumption or use by individuals for the purposes of personal care or in or about the household or in connection with personal possessions.) Note: Measurements that are part of an identity statement or a supplemental quantity statement on a part of a package other than the PDP do not have to be converted to metric units.

Metric Only Quantity Declarations are not Permitted in Most Cases -- There are two exceptions to this policy in the NCWM's Uniform Packaging and Labeling Regulation (UPLR) that permit metric only labeling in the case of small packages of seed and packages of camera film, video recording tape, audio recording tape, and other image and audio recording media intended for retail sale and consumer use.

Use SI Units -- The metric units required to be used are those of the International System of Units (SI) as established in 1960 by the General Conference on Weights and Measures and interpreted or modified for the United States by the Secretary of Commerce. [See National Institute of Standards and Technology Special Publication 814, Metric System of Measurement; Interpretation of the International System of Units for the United States or the Federal Register of December 20, 1990 (FR 90-21913), or subsequent revisions.]

Exemptions -- The requirements for statements of quantity in both inch-pound and SI units do not apply to:

  • Foods packaged at the retail store level
  • Random weight packages and uniform weight packages of cheese and cheese products labeled in the same manner and by the same type of equipment as random packages
  • Package labels printed before February 14, 1994
  • Meat and poultry products subject to the Federal Meat or Poultry products Inspection Acts
  • Tobacco or tobacco products
  • Any beverage subject to the Federal Alcohol Administration Act
  • Any product subject to the Federal Insecticide, Fungicide,and Rodenticide Act
  • Drugs subject to the Federal Food, Drug and Cosmetic Act
  • Nonconsumer packages (any package other than a consumer package,and particularly a package intended solely for industrial or institutional use or for wholesale distribution)
  • Nutrition labeling information
  • Exports for foreign countries

When do the SI Metric Requirements Go Into Effect?

Effective Date -- The new requirements went into effect on February 14, 1994.

How Should the SI Metric Units be Displayed on Package Labels?

Which Unit Should be Shown First? -- Either the SI unit or the inch-pound unit may appear first.

Largest Whole Unit -- The SI declaration shall be in terms of the largest whole unit of weight or measure, with any remainder expressed in decimal fractions of such largest whole unit.

Use of the Terms "Net Weight" and "Net Mass" -- A quantity declaration may stand alone [e.g., "200 g (7 oz)" or "1 lb (453 g)"] or may include the term "net mass" or "net weight" either preceding or following the declaration. The term "net" by itself may be used on food labels. However, the quantity of contents shall always declare the net quantity of contents, even when such terms are not used.

An SI declaration:

  • in units of mass shall be in terms of the kilogram, gram, or milligram;
  • in units of liquid measure shall be in terms of the liter or milliliter, and shall express the volume at 20 oC, except in the case of petroleum products or distilled spirits, for which the declaration shall express the volume at 15.6 oC, and except also in the case of a commodity that is normally sold and consumed while frozen, for which the declaration shall express the volume at the frozen temperature, and except also in the case of malt beverages or a commodity that must be maintained in the refrigerated state, for which the declaration shall express the volume at 4 oC;
  • in units of linear measure shall be in terms of the meter, centimeter, or millimeter (except that, micrometer is used when the declaration is less than 1 mm);
  • in units of area measure, shall be in terms of the square meter, square decimeters, square centimeter, or square millimeter;
  • in units of volume other than liquid measure, shall be in terms of the liter and milliliter, except that the terms cubic meter and cubic centimeter shall be used only when specifically designated as a method of sale;

Rule of 1000 -- The selected multiple or submultiple prefixes for SI units shall result in numerical values between 1 and 1000. This rule allows centimeters or millimeters to be used where a length declaration is less than 100 centimeters. For example: 500 g not 0.5 kg; 1.96 kg not 1960 g; or 750 mL, not 0.75 L, or 750 mm or 75 cm, not 0.75 m;

Number of Digits -- SI declarations should be shown in three digits except where the quantity is below 100 grams, milliliters, centimeters, square centimeters, or cubic centimeters, where it can be shown in two digits. In either case, any final zero appearing to the right of the decimal point need not be shown.

Symbols -- The following symbols for SI units, and none other, may be used in the quantity statement on a package of commodity: (Note: These requirements apply only to quantity declarations; see FDA regulations for symbols permitted on nutrition labels.)

centimeter cm cubic meter m3
cubic centimeter cm3 kilogram kg
meter m gram g
milligram mg millimeter mm
liter L or l square meter m2
mililiter mL or ml cubic decimeter dm3
square centimeter cm2 square decimeter dm2
micrometer µm


Capitalization, Plurals
-- Symbols, except for liter, are not capitalized unless the unit is derived from a proper name. Periods shall not be used after the symbol. Symbols shall always be written in the singular formit is not acceptable to add "s" to an SI symbol to express the plural of the symbol.

Symbols for Liter, Milliliter -- The "L" symbol and the "mL" symbol are preferred; however, the "l" symbol for liter and "ml" symbol for milliliter are permitted.

  • Fractions -- An SI statement in a declaration of net quantity of contents of any consumer commodity may contain only decimal fractions.
  • Prefixes -- The following chart indicates SI prefixes that may be used on a broad range of consumer commodity labels to form multiples and submultiples of SI units:
Prefix Symbol Multiplying Factor*
kilo- k × 103
deca-** da × 10
deci- d × 10-1
centi-*** c × 10-2
milli- m × 10-3
micro-**** µ × 10-6
*102 =100; 103 =1000; 10-1 = 0.1; 10-2 =0.01
Thus, 2 kg=22 × 1000 g=2000 g and 3 cm=3 × 0.01 m=0.03 m
**Not permitted on food labels.
***Should be used only with "Meter."
****Shall only be used for measurements less than 1 mm.

Prescribed Units - SI units:

  • Less than 1 meter, 1 square meter, 1 kilogram, 1 cubic meter, or 1 liter shall be expressed as follows:
    1. length measure of less than 1 meter: in centimeters or millimeters;
    2. area measure of less than 1 square meter: in square decimeters and fractions of a square decimeter or in square centimeters and fractions of a square centimeter;
    3. mass of less than 1 kilogram: in grams and fractions of a gram, but if less than 1 gram, then in milligrams;
    4. liquid or dry measure of less than 1 liter: in milliliters;
    5. ubic measure less than 1 cubic meter: in cubic centimeters or cubic decimeters (liters);
  • provided, the quantity declaration appearing on a random mass package may be expressed in terms of decimal fractions of the largest appropriate unit, the fraction being carried out to not more than three decimal places.
  • One meter, 1 square meter, 1 kilogram, 1 cubic meter, or 1 liter or more -- In the case of:
    1. length measure of 1 meter or more: in meters and decimal fractions to not more than three places;
    2. area measure of 1 square meter or more: in square meters and decimal fractions to not more than three places;
    3. mass of 1 kilogram or more: in kilograms and decimal fractions to not more than three places;
    4. liquid or dry measure of 1 liter or more: in liters and decimal fractions to not more than three places.
    5. cubic measure of 1 cubic meter or more: in cubic meters and decimal fractions to not more than three places.
  • Bidimensional commodities -- For bidimensional commodities (including rolltype commodities), the SI quantity declaration shall be expressed:
    1. if the area is less than 929 cm2 (1 sq ft), in terms of length and width (expressed in the largest whole unit);
    2. if the area is at least 929 cm2 (1 sq ft) but less than 37.1 dm2 (4 sq ft), in terms of area (expressed in the largest whole unit) followed by a declaration of length and width in terms of the largest whole unit, provided:
      1. for bidimensional commodities having a width of 10 cm (4 in) or less, the declaration of net quantity shall be expressed in terms of width and length only;
      2. commodities consisting of usable individual units (except rolltype commodities with individual usable units created by perforations, for which see UPLR § 6.10. Count: Ply.) require a declaration of unit area but not a declaration of total area of all such units.
    3. if the area is 37.1 dm2 (4 sq ft) or more, in terms of area (expressed in terms of the largest whole unit) followed by a declaration of the length and width, in terms of the largest whole unit; provided no declaration of area is required for a bidimensional commodity with a width of 10 cm (4 in) or less.
    4. no declaration in square units is required for commodities for which the length and width measurements are critical in terms of end use (such as wallpaper border) if such commodities clearly present the length and width measurements on the label.
      1. Rounding -- In all conversions for the purpose of showing an equivalent SI or inch-pound quantity to a rounded inch-pound or SI quantity, or in calculated values to be declared in the net quantity statement, the number of significant digits retained must be such that accuracy is neither sacrificed nor exaggerated. Conversions, the proper use of significant digits, and rounding must be based on the packer's knowledge of the accuracy of the original measurement that is being converted. In no case shall rounded net contents declarations overstate a quantity; the packer may round converted values down to avoid overstating the net contents. (See the attached Appendixes A & B from the UPLR.) Note: When as a result of rounding SI or customary inch-pound declarations calculated based on the conversion factors in Appendix A, the resulting declarations are not exact, the largest number will be used for enforcement purposes to determine whether a package contains at least the declared amount of product.
      2. Minimum Height of Numbers and Letters -- The height of any letter or number in the required quantity declaration shall be not less than that shown in Table 1 below, with respect to the area of the panel, and the height of each number of a common fraction shall meet one-half the minimum height standards. When upper and lower case, or all lowercase letters are used in SI symbols, it is the uppercase "L," lowercase "d," or their equivalent in the print or type that shall meet the minimum height requirement. However, no letter shall be less than 1.6 mm (1/16 in) in height. Other letters and exponents must be presented in the same type style and in proportion to the type size used.

      3. Table 1. Minimum Height of Numbers and Letters
        Area of principal display panel Minimum height of numbers and letters Minimum height: label
        information blown, formed, or
        molded on surface on container
        <= 32 cm² (5 in²)
        1.6 mm (1/16 in)
        3.2 mm (1/8 in)
        > 32 cm² (5 in²) <=161 cm² (25 in²)
        3.2 mm (1/8 in)
        4.8 mm (3/16 in)
        > 161 cm² (25 in²) <=645 cm² (100 in²)
        4.8 mm (3/16 in)
        6.4 mm (1/4 in)
        > 645 cm² (100 in²) <=2581 cm2 (400 in²)
        6.4 mm (1/4 in)
        7.9 mm (5/16 in)
        > 2581 cm² (400 in²)
        12.7 mm (1/2 in)
        14.3 mm (9/16 in)
        Symbols: <= means less than or equal to; < means less than; > means greater than
        Note: The type size requirements specified in this table do not apply to the "e" mark.

      4. For Complete Information on Packaging and Labeling Requirements: See National Institute of Standards and Technology (NIST) Handbook 130, Uniform Laws and Regulations, or the applicable Federal, State, or local regulations for additional packaging and labeling requirements. Copies of Handbook 130 may be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402 (Tele. no.: 202-783-3238). Copies may also be obtained as a benefit of membership in the NCWM.

UPLR Appendix A: SI/Inch-Pound Conversion Factors

UPLR Appendix B:Converting Inch - Pound Units to SI Units for Quantity Declarations on Packages

Conversion - To convert an inch-pound quantity to an SI quantity, multiply the appropriate conversion factor in Table 1 in Appendix A by the inch-pound unit and round according to the following rules.

Rounding and Significant Digits - It is the packager's responsibility to round converted values appropriately and select the appropriate number of significant digits to use in quantity declaration. [These rounding rules are for converting quantity determinations on packages and do not apply to digital scales that automatically round indications to the nearest indicated value.] Conversions, the proper use of significant digits, and rounding must be based on the packer's knowledge of the accuracy of the original measurement that is being converted. For example; if a package is labeled 453.59 g (1 lb), the packer is implying that the package declaration is accurate within ± 0.005 g (or ± 5 mg). For liquid volume measure, a label declaration of 473 mL (16 fl oz) implies that the package declaration is accurate to within ± 0.5 mL (0.01 fl oz). The requirements of § 6.13. Rounding apply to all quantity declarations that are derived from converted values:

6.13. Rounding. -- In all conversions for the purpose of showing an equivalent SI or inch-pound quantity to a rounded inch-pound or SI quantity, or in calculated values to be declared in the net quantity statement, the number of significant digits retained must be such that accuracy is neither sacrificed nor exaggerated. Conversions, the proper use of significant digits, and rounding must be based on the packer's knowledge of the accuracy of the original measurement that is being converted. In no case shall rounded net contents declarations overstate a quantity; the packer may round converted values down to avoid overstating the net contents.
Note: When as a result of rounding SI or customary inch-pound declarations calculated based on the conversion factors in Appendix A, the resulting declarations are not exact, the largest number will be used for enforcement purposes to determine whether a package contains at least the declared amount of product.

Do not round conversion factors or any other quantity used or determined in the calculation; only round the final quantity to the number of significant digits needed to maintain the accuracy of the original quantity. Use the rounding rules presented below in Table 1 as guidance to round the final result. In general, quantity declarations on consumer commodities should only be shown to two or three significant digits (for example, 453 g or 85 g). Any final zeros to the right of the decimal point need not be expressed. The inch-pound and SI declarations of quantity must be accurate and equivalent to each other. For example, a package bearing a net weight declaration of 2 lb (32 oz) must also include an SI declaration of 907 g.

Table 2. Rounding Rules
When The First Digit Dropped is: The Last Digit Retained is: Examples
Less than 5 Unchanged 2.44 to 2.4
2.429 to 2.4
More than 5, or 5 followed by at least 1 digit other than 0 Increased by 1 2.46 to 2.5
2.51 to 2.5
5 followed by zeros Unchanged if Even, or increased by 1 if Odd 2.450 to 2.4
2.550 to 2.6

  1. When the first digit discarded is less than five, the last digit retained should not be changed. For example, if the quantity 984.3 is to be declared to three significant digits, the figure 3 to the right of the decimal point must be discarded since it is less than 5 and the last digit to be retained (the figure "4") will remain unchanged. The rounded number will read 984. The same rationale applies to numbers declared to two significant digits (for example 68.4 and 7.34); again the final digit is dropped and the last digit retained remains unchanged so that the "rounded-off" numbers become 68 and 7.3 respectively.
  2. When the first digit to be discarded is greater than five, or it is a five followed by at least one digit other than zero, the last digit to be retained should be increased by one unit.
    Examples:
    984.7 becomes 985
    984.51 becomes 985
    6.86 becomes 6.9
    6.88 becomes 6.9
  3. When the first digit to be discarded is exactly five, followed only by zeros, the final digit to be retained should be rounded up if it is an odd number (1,3,5,7, or 9), but no adjustment should be made if it is an even number (2,4,6, or 8).
    Examples:
    984.50 becomes 984
    985.50 becomes 986
    68.50 becomes 68
    7.450 becomes 7.4
    7.550 becomes 7.6
    *Note: See additional examples on page 9.

Additional Advice on Rounding and Significant Digits

  1. These rules require the packer to use good judgement in making decisions on how to round and the number of significant digits to use in quantity declarations. Rounding should always be done in one step; for example, if 16.94647 g has to be rounded to 3 significant digits, it should be rounded to 16.9 g, not 16.9465, then to 16.946, then to 16.95 which would then round to 17.0 g (See rounding rules above).
  2. Do not use rounded SI values to calculate quantities. For example, using 1 inch = 25.4 mm, rounded to 25 mm, should not be multiplied by 2 to determine the SI equivalent for 2 inches. The SI equivalent for 2 in is determined by multiplying 2 in x 25.4 mm = 50.8 mm, then rounding to 51 mm.
  3. If a dimension given as 8 feet is valid to the nearest 1/10 inch, consider it to mean 96.0 inches and treat it as having 3 significant digits. The rounded dimension would then be 2.44 m instead of 2.4 m.
  4. Conversions using a multiple digit conversion factor usually give a product with more digits than the original quantity. The final product should contain no more significant digits than are contained in the number with the fewest significant digits used in the conversion. For example, the area of a sheet of paper is determined on a calculator by multiplying 1.25 cm (length) x 1.5 cm (width) = 1.875 cm2. The product given to 4 significant digits on the calculator cannot be any more accurate than 2 significant digits (the number of significant digits in 1.5 cm), so the area should be declared as 1.9 cm2.
  5. Packagers of consumer commodities should be aware that when a converted value is rounded up, there may be a need to (1) increase the package contents and/or, (2) select a converted value that does not exaggerate the precision of the quantity or overstate the net contents. For example, under the rules above, a net weight declaration of 16 oz (453.592 37 g) would be rounded up 0.4 g to 454 g for 3 significant digits. Inspections by weights and measures officials are typically conducted using devices with a resolution of 0.5 g or less. If the packer does not address this possibility, some lots of commodities may pass when the inch-pound declaration is tested, but fail when the SI declaration is verified.