International Envelope Paper Sizes

DL 220 × 110 mm C7 114 × 81 mm C7/C6 162 × 81 mm C6 162 × 114 mm C6/C5 227 × 114 mm C5 229 × 162 mm C4 324 × 227 mm C3 458 × 324 mm B6 176 × 125 mm B5 250 × 176 mm B4 353 × 250 mm E4 400 × 280 mm

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 × Height (mm)	Width × Height (in)
DL	220 × 110 mm	8.661 × 4.331 in
C7	114 × 81 mm	4.488 × 3.189 in
C7/C6	162 × 81 mm	6.378 × 3.189 in
C6	162 × 114 mm	6.378 × 4.488 in
C6/C5	227 × 114 mm	8.937 × 4.488 in
C5	229 × 162 mm	9.016 × 6.378 in
C4	324 × 227 mm	12.756 × 8.937 in
C3	458 × 324 mm	18.031 × 12.756 in
B6	176 × 125 mm	6.929 × 4.921 in
B5	250 × 176 mm	9.843 × 6.929 in
B4	353 × 250 mm	13.898 × 9.843 in
E4	400 × 280 mm	15.748 × 11.024 in