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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 × 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