This is part of the Labeling Basics series in which I am taking labeling back to its most fundamental parts, starting with the legal terms used and then going on to each requirement for soap and cosmetic labels.

In labeling, the size and placement of the principal display panel determines where certain information must be placed and what size the text must be.


Of a thing: first, chief, most important.

Display Panel:

A separate or distinct part of a surface on which information can be shown.

Principal Display Panel (PDP):

The part of a label that is most likely to be displayed, presented, shown, or examined under normal and customary conditions of display for retail sale.1Definition from regulations at 16 CFR 500.2(h) and 21 CFR 701.10

Usually it is the front panel of the package or container. It’s what the consumers see as they walk by or what they would be most likely to read first when picking up and inspecting the product.

The PDP must be large enough to accommodate all the mandatory label information clearly and conspicuously and without obscuring designs, pictures, or crowding.221 CFR 701.10

If the actual product container is inside a box, only the outer package (in this case, the box) has a PDP.321 CFR 701.10

Calculating the Size of the PDP

The size of the PDP is calculated in square inches.

Rectangular Package

For a rectangular package or container, the principal display panel is one entire side.4UPLR 8.2(a) and  21 CFR 701.10(a) and 16 CFR 500.21(a)(1) The size is calculated as the width x height of that side.5UPLR 8.2(a) and  21 CFR 701.10(a) and 16 CFR 500.21(a)(1)

height x width = PDP

Example: For a soap box that is 2″ high and 3.5″ wide, the PDP is calculated as:
2″ x 3.5″ = 7 sq. inches

Calculating the PDP size for a rectangular package.

Cylindrical Container

For the PDP of a cylindrical container, the PDP size is 40% of the entire surface (excluding shoulder and neck). It is calculated by multiplying the height times the circumference and then calculating 40% (.4) of that space.621 CFR 701.10(b) and 16 CFR 500.2(h) and UPLR 8.2(b)

Circumference: The measurement around a round or circular object.

(height x circumference) x 40% = PDP

For example, a bottle that is 3″ high and 6″ around would be calculated as:
(3″ x 6″) x 40% = 7.2 sq. inches

Otherwise Shaped Containers

In the case of any otherwise shaped container or commodity, the PDP is 40% of the total surface space.  HOWEVER, if there is a side or panel that is an obvious principal panel, such as one side of a triangular shaped box, then that would be considered the entire PDP.721 CFR 701.10(a)(3)

Very Small Containers

Very small containers (for example, a 1/4 oz vial) may use a tear-away tag or tape to present the required information. In that case, the PDP size is determined by the container itself. If the small container is attached to a larger card which contains the necessary information, then the card to which the container is attached is considered the PDP.816 CFR 500.2(h)

Why is it Important?

The size of the principal display panel is used to determine:

  • Required text size of the statement of net contents
  • Placement of the statement of net contents


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