C8 Envelope Size
C8 measures 57 × 81 mm (2.24 × 3.19 in). The C series is used for envelopes.
| Millimetres | 57 × 81 mm |
|---|---|
| Centimetres | 5.7 × 8.1 cm |
| Inches | 2.24 × 3.19 in |
| Aspect ratio (long ÷ short) | 1.421 |
| Series | ISO 269 C series (envelopes) |
| Fits | An A8 sheet laid flat fits inside a C8 envelope |
| Fits inside | A C8 envelope fits inside a B8 envelope |
Where you will see C8
C8 is a small envelope for A8-size cards and tags.
How C8 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 (52 × 74 mm for A8), so a flat A8 sheet fits inside a C8 envelope. The C8 envelope in turn fits inside a B8 envelope (62 × 88 mm).
Frequently asked questions
What size is a C8 envelope?
A C8 envelope is 57 × 81 mm (2.24 × 3.19 inches).
What fits in a C8 envelope?
A flat A8 sheet (52 × 74 mm) fits in a C8 envelope with a small margin of 5 mm in width and 7 mm in height.
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Last updated: 2026-10-03