Plate Number

A plate number identifies the printing plate used to produce a sheet of stamps. It is most often printed in the sheet margin, but on some issues it appears within the stamp design. Plate numbers help printers keep track of plates and help collectors identify printings and positional varieties.

Plate Numbers in Margins

On many issues, the plate number appears once or several times in the sheet margins, usually next to a corner stamp. Collectors save:

• Plate number singles — a single stamp with the numbered margin attached.
• Plate blocks — a block of stamps with the numbered margin, typically four or six stamps in US practice.
• Matched sets — plate blocks from each corner of the same sheet.

With photogravure printing, the equivalent is a cylinder number, and British collectors save cylinder blocks in the same way.

Plate Numbers in the Design

Some classic British stamps carry the plate number engraved into the design itself. The best-known example is the Penny Red of 1864–1879, with the plate number in the side ornaments. Collecting one example from every plate — about 150 in total — is a long-standing challenge. Plate 77 was prepared but its sheets were rejected; only a handful of copies are known, making it one of Britain’s great rarities.

Plate Number Coils

In the United States, many coil stamps from 1981 onward carry a small plate number at regular intervals along the roll. Plate number coils (PNCs) are collected as singles or strips of three or five and have their own dedicated community and catalogues.

Why Plate Numbers Matter

Plate numbers can:

• Distinguish printings with different colours or papers.
• Locate plate flaws on specific plates and positions.
• Date printings when plates were used in sequence.
• Identify scarce plates that produced relatively few sheets.