Principal Display Panel: The Panel Area Sets the Smallest Legal Type

Measure the front of a carton, multiply height by width, and the answer decides how small the net weight can go. That is the whole mechanism, and it runs one way only.

So the smallest letter on the package is not a design decision but arithmetic, and the arithmetic starts with a single face of the box.

Published guides reproduce the type table readily enough, but far fewer explain the step before it, which works out the area that picks the row.

And that is where the care belongs. The rule throws away tops, bottoms, can flanges and the shoulders and necks of bottles, then keeps two fifths of the rest on anything that is not a rectangle.

It is also where the agencies part company. Four of them publish the same heights against the same brackets, and one offers a second way to measure a cylinder.

This reference covers what counts as the panel, how its area works out, the brackets that turn area into letter height, and why a declared weight is an average.

The Panel Is Not the Package

The principal display panel is whichever part of a label a shopper meets under the customary conditions of retail display. That is a functional test rather than a geometric one, and it comes first.

A rectangular package answers it simply, since one entire side serves as the panel and its area is height times width of that side.

Which face, though, is the one that faces out. A tall narrow carton and a flat wide one can carry the same three box dimensions in a different order, so the panel follows display rather than the drawing.

Then come the exclusions, and they matter more than they look. Tops and bottoms do not count, can flanges do not count, and neither do the shoulders or necks of bottles and jars.

So the usable panel runs smaller than the package, sometimes much smaller. A squat jar with broad shoulders gives up a good deal of its wrap before the sum even begins.

Forty Percent of Anything That Is Not a Box

Away from rectangles the rule stops measuring a face and starts taking a fraction. For a cylindrical or nearly cylindrical container, the panel is 40 percent of the height times the circumference.

Read that as a share of the whole wrap. A can has no natural front, so the rule assumes a shopper sees about two fifths of it at once and gives you that much to work with.

Other shapes get the same treatment against total surface, at 40 percent of the container’s total area, with the same tops, bottoms, flanges and necks coming out first.

One exception runs the other way, and it is generous. Where the container has an obvious panel, such as the top of a triangular or circular package, the entire top counts instead of a fraction.

That exception can cut either way. Claiming the whole top gives a bigger area than 40 percent of the surface would, and a bigger area forces a bigger letter.

The Area Picks the Letter

With a square-inch figure in hand the rest is a lookup. Four brackets cover every package, and each one sets a floor rather than a size.

Panel area	Minimum letter height
5 sq in or less	1/16 in (1.5 mm)
Over 5 to 25 sq in	1/8 in (3.1 mm)
Over 25 to 100 sq in	3/16 in (4.7 mm)
Over 100 sq in	1/4 in (6.35 mm)
Over 400 sq in	1/2 in (12.7 mm)

Notice what happens at the last step, because crossing 400 square inches doubles the floor from a quarter inch to a half.

No other bracket behaves that way, since the earlier steps rise by a sixteenth at a time and the last one jumps by the whole previous requirement.

Which makes a modest enlargement expensive on a large carton. A panel at 395 square inches needs a quarter-inch letter, and the same carton grown slightly needs twice that.

Which Letter Gets Measured

A height requirement means nothing until the rule says which letter it governs, and the answer catches people out.

Heights refer to capital letters by default. But where the text runs mixed case or all lower case, the lower case letter o, or its equivalent, has to meet the standard.

So a designer measuring the cap height of a mixed-case line measures the wrong letter. The o stands shorter than the cap, which means the type must be set larger than the stated figure.

Fractions get a concession, since each component numeral of a fraction need only reach half the minimum height.

Raised type gets a penalty instead. Blown, embossed or molded type on glass or plastic adds a further sixteenth of an inch to every size in the table.

And the letters will not squeeze to fit. The ratio of height to width may not exceed three units to one, so no letter stands more than three times as high as it is wide.

Metric symbols follow a line of their own. Where the declaration carries SI units, the upper case L, the lower case d or their equivalent must meet the minimum, and no letter may fall below 1.6 mm. The estimated-quantity e mark escapes the sizes altogether.

Four Tables Agree, One Area Rule Does Not

Several agencies regulate package declarations, split by what sits inside. This site usually finds their numbers disagreeing, but here the numbers match and the method does not.

Rule	Covers	Same letter table	Cylinder panel
16 CFR 500.21	Non-food consumer goods	Yes	40% of height x circumference
21 CFR 101.1, 101.7	Food	Yes	40% of height x circumference
21 CFR 701.13	Cosmetics	Yes	—
9 CFR 317.2	Meat	Yes	40%, or one third of the circumference
9 CFR 381.116	Poultry	—	40%, or one third of the circumference

The meat labeling rule and its poultry counterpart hand a cylinder two measurements. One is the familiar 40 percent of height times circumference, and the other is a panel one third of the circumference wide and as high as the container.

Those are not the same number. One third works out at 33.3 percent of height times circumference against 40 percent, so the second option yields the smaller panel.

A smaller panel can fall in a lower bracket, and that is where it gets interesting. Take a can three inches across and seven inches tall, giving a circumference of 9.42 inches and a height times circumference of 65.97 square inches.

Run both methods. The 40 percent figure is 26.39 square inches, which lands just above 25 and calls for three sixteenths. The one third figure is 21.99 square inches, which lands below 25 and calls for an eighth.

Same can, same contents, and a legal letter half a step smaller on one reading. That election exists only for meat and poultry, so an identical can of soup and an identical can of stew can carry different minimum type.

Cosmetics get a concession of their own. Where a cosmetic sells in an outer and an inner container that both carry the required information, and the inner never sells alone, the rule waives placement for it.

Two further points decide which rule applies. Food falls to the FDA, the agency behind the rules on food contact paperboard, so one carton can answer to both at once. And a declaration that misses these sizes counts as misbranded, which is the footing tamper-evident packaging stands on too.

The Bottom Thirty Percent, and an Average

The rule fixes placement as well as size. The declaration belongs within the bottom 30 percent of the panel, in lines generally parallel to the base the package rests on, and set apart from the text around it. Panels of five square inches or less escape that placement.

The quantity itself is softer than it looks, because the rule allows variations that come from ordinary exposure in good distribution practice, or from unavoidable deviations in good packaging practice.

But the softness has a hard edge. The permitted variation may not run so far that the average across a shipment drops below the stated quantity. And no unreasonable shortage in any one package passes, even where overages elsewhere make up for it.

Common Questions