C Envelope paper sizes
- C5162 x 229mm
- C4229 x 324mm
- C6114 x 162mm
- C3324 x 458mm
- C781 x 114mm
- C2458 x 648mm
- C857 x 81mm
- C1648 x 917mm
- C940 x 57mm
- C0917 x 1297mm
- C1028 x 40mm
Further Information
The dimensions of the C series sizes are defined by the ISO 269 paper size standard. The C series is most commonly 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, C4 has a bigger area than A4, but smaller area than B4. Therefore an A4 piece of paper will fit into a C4 envelope. The aspect ratio of C series envelopes is 1:√2, and this means that an A4 sheet of paper when folded in half, parallel to its smaller sides, will fit nicely into a C5 envelope. When it is folded twice, it will fit into a C6 envelope, and so on.
| Format | Width x Height (cm) | Width x Height (in) |
| C5 | 162 x 229 | 6.4 x 9 |
| C4 | 229 x 324 | 9 x 12.8 |
| C6 | 114 x 162 | 4.5 x 6.4 |
| C3 | 324 x 458 | 12.8 x 18 |
| C7 | 81 x 114 | 3.2 x 4.5 |
| C2 | 458 x 648 | 18 x 25.5 |
| C8 | 57 x 81 | 2.2 x 3.2 |
| C1 | 648 x 917 | 25.5 x 36.1 |
| C9 | 40 x 57 | 1.6 x 2.2 |
| C0 | 917 x 1297 | 36.1 x 51.1 |
| C10 | 28 x 40 | 1.1 x 1.6 |