C Envelope Paper Sizes


C Envelope Sizes Information C Envelope Paper Sizes

C series paper sizes and dimensions are defined by the ISO 269 international paper size standard. The C series is usually used for envelopes. The area of C series paper is the geometric mean of the areas of the A and B series paper of the same number. For example, the area of a C4 sheet is the geometric mean of the areas of an A4 sheet and a B4 sheet. This means that C4 is bigger than A4, and somewhat smaller than B4. The practical usage of this is that a letter written on A4 paper fits inside a C4 envelope, and both A4 and C4 paper fits inside a B4 envelope.

Format Width × Height (mm) Width × Height (in)
C0 917 x 1297 mm 36.1 x 51 in
C1 648 x 917 mm 25.5 x 36.1 in
C2 458 x 648 mm 18 x 25.5 in
C3 324 x 458 mm 12.8 x 18 in
C4 229 x 324 mm 9 x 12.8 in
C5 162 x 229 mm 6.4 x 9 in
C6 114 x 162 mm 4.5 x 6.4 in
C7 81 x 114 mm 3.2 x 4.5 in
C8 57 x 81 mm 2.2 x 3.2 in
C9 40 x 57 mm 1.6 x 2.2 in
C10 28 x 40 mm 1.1 x 1.6 in