A plate number coil is a United States postage stamp with the number of the printing plate on it. The number is at the bottom of the stamp and gives the number of the printing plate used to produce the stamp.

The plate number is on one stamp out of the number of stamps printed by a single revolution of rotary printing press used to print the stamps.

PNC is an abbreviation of plate number coil.

Most collectors save plate number coils in the following formats:

  1. PNC5 - Plate Number Coil 5 - A strip of 5 mint stamps with the plate number coil on the center stamp.
  2. PNC3 - Plate Number Coil 3 - A strip of 3 mint stamps with the plate number coil on the center stamp. A PNC3 is less desirable than a PNC5
  3. PNS - Plate Number Single - A single used plate number coil stamp. The plate number must be identifiable and not be obliterated by the postmark.
  4. On cover - An envelope bearing a used plate number coil stamp with a postmark tying the stamp to the envelope. Many collectors prefer the cover to have the correct postage used for the envelope. This means they find stamp collector contrived or philatelic covers less desirable. Intentionally overpaying postage would be considered a philatelic cover.