Do I label my bottle in fluid ounces or by weight?

A pourable hot sauce is a liquid, so its net contents go in fluid measure, and federal law requires both US and metric units: "5 FL OZ (148 mL)" [3]. A thick, spoonable or chunky sauce, a paste or a chili crisp is declared by weight instead, as "NET WT 8 OZ (227 g)." The statement goes in the bottom 30 percent of the front panel, in type at least 1/16 inch tall on a small bottle, and it must state what is actually in the bottle, which is rarely the bottle's nominal size. This page covers the unit, the type size for your real bottle and checking fills.

Liquid, viscous or in between

21 CFR 101.7 sets the basic split. A liquid food is declared in fluid measure. A solid, semisolid or viscous food, or a mixture of solid and liquid, is declared by weight [1]. Hot sauces cover that whole range, so decide by how your product behaves:

If you cannot decide for a product in the middle row, ask your state food program or weights and measures office before you print, and keep the answer in writing. Whatever you choose, use the same basis every time you label that product.

For a container under 1 gallon or 4 pounds, the declaration is in ounces, with pounds or quarts added in parentheses only for larger sizes [1]. ### US and metric units: print both

The two federal texts read differently here. FDA's regulation, 21 CFR 101.7, still says a metric statement "may" appear with the US units [1]. The Fair Packaging and Labeling Act, as amended in 1992, goes further: 15 U.S.C. 1453(a)(2) requires the net quantity in the most appropriate units of both the customary inch/pound system and the SI metric system [3]. The statute controls, so print both. It names two exceptions that rarely touch a bottled hot sauce: random-weight packages, labeled in pounds and decimal fractions of a pound, where the metric statement is optional (1453(a)(3)(A)(ii)), and foods packaged at the retail store level (1453(a)(6)) [3].

Round the metric figure sensibly: 1 US fluid ounce is 29.57 mL, so 5 fl oz is 147.9 mL and is printed as 148 mL; 1 ounce by weight is 28.35 g, so 8 oz is printed as 227 g.

Placement and type size on a small bottle

The net quantity has to be a separate item on the principal display panel, set apart from other text, and placed within the bottom 30 percent of that panel [1]. On a panel of 5 square inches or less, the bottom-30-percent rule does not apply, though every other rule does [1].

Minimum type height depends on the area of the principal display panel [1]:

Three details catch people out. The letters can be no more than three times as high as they are wide, which rules out very condensed fonts [1]. Each part of a fraction must be at least half the minimum height [1]. And if the quantity is molded or embossed into the glass rather than printed, it must be 1/16 inch larger than the table requires [1]. The type must be bold or in clear contrast to the background [1].

Measuring the panel on a round bottle

For a cylindrical bottle, the principal display panel is 40 percent of the container's height multiplied by its circumference, and the shoulders and neck are left out [2]. Measure your own bottle; do not rely on a catalog drawing. Here is the arithmetic with illustrative dimensions for a slim 5 oz bottle:

1. Height of the straight body, excluding shoulder and neck: 3.0 inches.
2. Diameter of the body: 1.75 inches, so the circumference is 3.1416 × 1.75 = 5.50 inches.
3. Principal display panel area: 0.40 × 3.0 × 5.50 = 6.6 square inches.
4. 6.6 square inches falls in the "more than 5, up to 25" band, so the net quantity type must be at least 1/8 inch tall.
5. Because the panel is over 5 square inches, the statement must sit in the bottom 30 percent of the panel.

A slightly smaller bottle could fall under 5 square inches and drop to the 1/16 inch minimum. That is why the same artwork cannot simply be shrunk from a 10 oz bottle onto a 5 oz one.

Declaring what the bottle actually holds

Bottles are sold by a nominal size, and the nominal size is only a name. A "5 oz" woozy holds somewhat more than 5 fluid ounces when filled to the brim (its overflow capacity) and somewhat less when filled to a practical level with headspace under the cap. Your label declares the sauce in the bottle, so the number on the label comes from your filling, not from the bottle supplier's description [1].

Three things decide what you can honestly declare:

• Your fill height. Hot fill and inversion need some headspace, and your scheduled process may set it. The headspace page covers how full to fill.
• Cooling. Hot-filled sauce contracts as it cools, so the level drops after capping. Declare what is there at room temperature.
• Consistency. Hand filling varies from bottle to bottle. Pick a target fill a little above the declared amount so that your lightest bottles still meet it.

If the honest fill of your bottle is 4.8 fluid ounces, declare 4.8 fl oz or move to a bottle that holds 5 at your fill height. Choosing between bottle sizes and shapes is on the bottle sizes page.

Checking fills with a scale

Volume is hard to check on a production table. Weight is easy. Convert your declared volume to a target weight once, then check bottles on a scale.

1. Measure the density of your sauce. At room temperature, tare a graduated cylinder or a measuring vessel you trust, add exactly 100 mL of finished sauce, and weigh it. Repeat three times and average. A sauce that weighs 105 g per 100 mL has a density of 1.05 g/mL. Density changes with formula and thickener, so measure each product.
2. Work out the target net weight. Declared volume in mL × density. For 5 fl oz (147.9 mL) at 1.05 g/mL, the net weight is 155.3 g.
3. Weigh empty bottles and caps. Weigh ten empty bottles with caps and orifice reducers and note the heaviest. Glass weight varies more than you might expect.
4. Set your check weight. Heaviest empty package plus target net weight, plus a small margin for your filling variation. Record it on the batch record.
5. Check during the run. Weigh a sample of filled, capped, cooled bottles at intervals (for example the first ten, then one in twenty) and record the results with the lot code.

These weights also feed your yield math. If a batch fills fewer bottles than you expected, the yield page shows where the weight went.

When the label has to change

Change the net quantity line whenever you change the bottle, the fill height or the declaration basis. For an acidified food, a new container size can also mean a new or amended process filing with FDA; that is covered on the when to refile page.

The rest of the front and back panel

Net contents is one of five required label elements. The statement of identity, the ingredient list, allergens and the name and address line are set out together on the federal labeling page, with the regulation for each.

References

1. eCFR, 21 CFR 101.7, Declaration of net quantity of contents, up to date as of October 20, 2026. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.7
2. eCFR, 21 CFR 101.1, Principal display panel of package form food, up to date as of October 20, 2026. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.1
3. U.S. Code, 15 U.S.C. 1453, Requirement of label information, paragraphs (a)(2), (a)(3)(A)(ii) and (a)(6), as amended by Pub. L. 102-329 (1992; effective February 14, 1994), GovInfo 2017 edition, read October 22, 2026. https://www.govinfo.gov/content/pkg/USCODE-2017-title15/html/USCODE-2017-title15-chap39-sec1453.htm