International Envelope Paper Sizes

Further Information

The standard envelope sizes are defined by the international standard ISO 269. They are generally designed to be used with paper sizes that follow the ISO 216 standard. The most commonly used envelope sizes are from the C series. An A4 piece of paper will fit into a C4 envelope. The DL envelope has a different aspect ratio to the C series, which is why it does not appear in that series. The DL envelope is the most common envelope used in business. DL is short for ‘Dimension Lengthwise’, however it was previously known as DIN Lang in Germany where it originated in the 1920s. An A4 sheet of paper folded three times, parallel to its smaller sides, will fit into a DL envelope.

Format Width x Height (mm) Width x Height (in)
DL 220 x 110 mm 8.7 x 4.3 in
C7 114 x 81 mm 4.5 x 3.2 in
C7/C6 162 x 81 mm 6.4 x 3.2 in
C6 162 x 114 mm 6.4 x 4.5 in
C6/C5 227 x 114 mm 8.9 x 4.5 in
C5 229 x 162 mm 9 x 6.4 in
C4 324 x 227 mm 12.8 x 8.9 in
C3 458 x 324 mm 18 x 12.8 in
B6 176 x 125 mm 6.9 x 4.9 in
B5 250 x 176 mm 9.8 x 6.9 in
B4 353 x 250 mm 13.9 x 9.8 in
E4 400 x 280 mm 15.7 x 11 in