C5 Envelope Size
C5 measures 162 × 229 mm (6.38 × 9.02 in). The C series is used for envelopes.
| Millimetres | 162 × 229 mm |
|---|---|
| Centimetres | 16.2 × 22.9 cm |
| Inches | 6.38 × 9.02 in |
| Aspect ratio (long ÷ short) | 1.414 |
| Series | ISO 269 C series (envelopes) |
| Fits | An A5 sheet laid flat fits inside a C5 envelope |
| Fits inside | A C5 envelope fits inside a B5 envelope |
Where you will see C5
C5 holds a flat A5 sheet, or an A4 sheet folded once. It is one of the most common envelope sizes for letters and cards.
How C5 relates to A and B sizes
In the ISO 269 C series, each C size is slightly larger than the A size with the same number (148 × 210 mm for A5), so a flat A5 sheet fits inside a C5 envelope. The C5 envelope in turn fits inside a B5 envelope (176 × 250 mm).
Frequently asked questions
What size is a C5 envelope?
A C5 envelope is 162 × 229 mm (6.38 × 9.02 inches).
What fits in a C5 envelope?
A flat A5 sheet (148 × 210 mm) fits in a C5 envelope with a small margin of 14 mm in width and 19 mm in height.
Related
- C4 Envelope Size229 × 324 mm
- C6 Envelope Size114 × 162 mm
- A5 Paper Size148 × 210 mm
- B5 Paper Size176 × 250 mm
Last updated: 2026-10-03