27 C.F.R. § 7.65 – Alcohol content.

(a) General. Alcohol content and the percentage and quantity of the original gravity or extract may be stated on any malt beverage label, unless prohibited by State law. When alcohol content is stated, and the manner of statement is not required under State law, it must be stated as prescribed in paragraph (b) of this section.
(b) How the alcohol content must be expressed. The following rules apply to both mandatory and optional statements of alcohol content.
1. (1) A statement of alcohol content must be expressed as a percentage of alcohol by volume. Other truthful, accurate, and specific factual representations of alcohol content, such as alcohol by weight, may be made, as long as they appear together with, and as part of, the statement of alcohol content as a percentage of alcohol by volume.
2. (2) For malt beverages containing one half of one percent (0.5 percent) or more alcohol by volume, statements of alcohol content must be expressed to the nearest one-tenth of a percentage point, subject to the tolerance permitted by paragraph (c) of this section. For malt beverages containing less than 0.5 percent alcohol by volume, alcohol content may be expressed either to the nearest one-tenth or the nearest one-hundredth of a percentage point, and such statements are not subject to any tolerance. See paragraph (e) of this section for the rules applicable to such statements.
3. (3)
  1. (i) The alcohol content statement must be expressed in one of the following formats:
    1. (A) “Alcohol percent by volume”;
    2. (B) “percent alcohol by volume”; or
    3. (C) “Alcohol by volume: percent.”
  2. (ii) Any of the words or symbols may be enclosed in parentheses and authorized abbreviations may be used with or without a period. The alcohol content statement does not have to appear with quotation marks.
4. (4) The statements listed in paragraph (b)(3) of this section must appear as shown, except that the following abbreviations may be used: Alcohol may be abbreviated as “alc”; percent may be represented by the percent symbol “%”; alcohol and volume may be separated by a slash “/” in lieu of the word “by”; and volume may be abbreviated as “vol”.
5. (5) Examples. The following are examples of alcohol content statements that comply with the requirements of this part:
  1. (i) “4.2% alc/vol”;
  2. (ii) “Alc. 4.0 percent by vol.”;
  3. (iii) “Alc 4% by vol”; and
  4. (iv) “5.9% Alcohol by Volume.”
(c) Tolerances. Except as provided by paragraph (d) of this section, a tolerance of 0.3 percentage points will be permitted, either above or below the stated alcohol content, for malt beverages containing 0.5 percent or more alcohol by volume. However, any malt beverage that is labeled as containing 0.5 percent or more alcohol by volume may not contain less than 0.5 percent alcohol by volume, regardless of any tolerance. The tolerance provided by this paragraph does not apply in determining compliance with the provisions of § 7.5 regarding the percentage of alcohol derived from added nonbeverage flavors and other nonbeverage ingredients containing alcohol.
(d) Low alcohol and reduced alcohol. The terms “low alcohol” or “reduced alcohol” may be used only on labels of malt beverages containing less than 2.5 percent alcohol by volume. The actual alcohol content may not equal or exceed 2.5 percent alcohol by volume, regardless of any tolerance permitted by paragraph (c) of this section.
(e) Non-alcoholic. The term “non-alcoholic” may be used on labels of malt beverages only if the statement “contains less than 0.5 percent (or .5%) alcohol by volume” appears immediately adjacent to it, in readily legible printing, and on a completely contrasting background. No tolerances are permitted for malt beverages labeled as “non-alcoholic” and containing less than 0.5 percent alcohol by volume. A malt beverage may not be labeled with an alcohol content of 0.0 percent alcohol by volume, unless it is also labeled as “alcohol free” in accordance with paragraph (f) of this section, and contains no alcohol.
(f) Alcohol free. The term “alcohol free” may be used only on malt beverages containing no alcohol. No tolerances are permitted for “alcohol free” malt beverages.