C0 Envelope Size
C0 measures 917 × 1297 mm (36.10 × 51.06 in). The C series is used for envelopes.
| Millimetres | 917 × 1297 mm |
|---|---|
| Centimetres | 91.7 × 129.7 cm |
| Inches | 36.10 × 51.06 in |
| Aspect ratio (long ÷ short) | 1.414 |
| Series | ISO 269 C series (envelopes) |
| Fits | An A0 sheet laid flat fits inside a C0 envelope |
| Fits inside | A C0 envelope fits inside a B0 envelope |
Where you will see C0
C0 is a very large envelope size, rarely used outside specialised mailing and packaging.
How C0 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 (841 × 1189 mm for A0), so a flat A0 sheet fits inside a C0 envelope. The C0 envelope in turn fits inside a B0 envelope (1000 × 1414 mm).
Frequently asked questions
What size is a C0 envelope?
A C0 envelope is 917 × 1297 mm (36.10 × 51.06 inches).
What fits in a C0 envelope?
A flat A0 sheet (841 × 1189 mm) fits in a C0 envelope with a small margin of 76 mm in width and 108 mm in height.
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Last updated: 2026-10-03