A standard poster board in the U.S. is typically 22 x 28 inches (about 56 x 71 cm).

Quick Scoop: Common Poster Board Sizes

  • Standard / classic school-project size: 22 x 28 inches.
  • Smaller boards: 11 x 14 inches and 14 x 22 inches are also common for tighter spaces or smaller displays.

In everyday use (school fairs, science projects, quick presentations), when someone says “poster board,” they almost always mean the 22 x 28 inch size.

Think of it like the “default” cereal box size at the store: others exist, but this is the one you see most on the shelf.