International Envelope Sizes
The international standard envelope size is defined by International standard ISO 269, but this standard has been revoked, and ISO 216 standard paper sizes are currently adopted, so the size of these envelopes is the same as the paper size of the corresponding format. The envelope sizes under international standards mainly include B series and C series, as shown in the table below.
International Standard Envelope Sizes
| Format | Width × Height (mm) | Width × Height (cm) | Width × Height (in) | AR |
|---|---|---|---|---|
| DL | 110 × 220 | 11 × 22 | 4 1⁄ 3× 8 2⁄ 3 | 2∶1 |
| C7 | 81 × 114 | 8.1 × 11.4 | 3 5⁄ 24× 4 1⁄ 2 | √2∶1 |
| C7/C6 | 81 × 162 | 8.1 × 16.2 | 3 5⁄ 24× 6 3⁄ 8 | 2∶1 |
| C6 | 114 × 162 | 11.4 × 16.2 | 4 1⁄ 2× 6 3⁄ 8 | √2∶1 |
| C6/C5 | 114 × 229 | 11.4 × 22.9 | 4 1⁄ 2× 9 | 2∶1 |
| C5 | 162 × 229 | 16.2 × 22.9 | 6 3⁄ 8× 9 | √2∶1 |
| C4 | 229 × 324 | 22.9 × 32.4 | 9 × 12 3⁄ 4 | √2∶1 |
| C3 | 324 × 458 | 32.4 × 45.8 | 12 3⁄ 4× 18 1⁄ 24 | √2∶1 |
| B6 | 125 × 176 | 12.5 × 17.6 | 4 11⁄ 12× 6 11⁄ 12 | √2∶1 |
| B5 | 176 × 250 | 17.6 × 25 | 6 11⁄ 12× 9 5⁄ 6 | √2∶1 |
| B4 | 250 × 353 | 25 × 35.3 | 9 5⁄ 6× 13 11⁄ 12 | √2∶1 |
| E4 | 280 × 400 | 28 × 40 | 11 1⁄ 24× 15 3⁄ 4 | 10∶7 |
