Series C Paper Size
| C Paper Size | Dimensions (inches) | Dimensions (mm) | Area (mm²) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| C0 Size | 36.1 × 51 | 917 × 1297 | 1189349 | ||||||
| C1 Size | 25.5 × 36.1 | 648 × 917 | 594216 | ||||||
| C2 Size | 18 × 25.5 | 458 × 648 | 296784 | ||||||
| C3 Size | 12.8 × 18 | 324 × 458 | 148392 | ||||||
| C4 Size | 9 × 12.8 | 229 × 324 | 74196 | ||||||
| C5 Size | 6.4 × 9 | 162 × 229 | 37098 | ||||||
| C6 Size | 4.5 × 6.4 | 114 × 162 | 18468 | ||||||
| C7 Size | 3.2 × 4.5 | 81 × 114 | 9234 | ||||||
| C8 Size | 2.2 × 3.2 | 57 × 81 | 4617 | ||||||
| C9 Size | 1.6 × 2.2 | 40 × 57 | 2280 | ||||||
| C10 Size | 1.1 × 1.6 | 28 × 40 | 1120 | ||||||
| Series C Paper Size Chart Maker : SSize.com | |||||||||
About Series C Paper Size
How are the standard size of C series paper defined?
The C series paper sizes are defined by the ISO 216 standard, which is the international standard for paper sizes. They are specifically designed as envelope sizes for the more common A series papers.
1. Primary Purpose.
The C series sizes are used primarily for envelopes, so that an A-size sheet (like A4) can fit comfortably inside a C-size envelope of the same number (e.g., an A4 letter fits into a C4 envelope).
2. Geometric Definition.
Each C size is the geometric mean between the corresponding A and B series sizes of the same number.
Geometric mean formula: If you have a length x from the A series and length y from the B series, the corresponding C dimension is √(x × y).
For example:
A4 dimensions: 210 × 297 mm
B4 dimensions: 250 × 353 mm
C4 dimensions: √(210 × 250) ≈ 229 mm and √(297 × 353) ≈ 324 mm
3. Key Property.
This geometric mean property ensures that:
An A4 sheet (210 × 297 mm) fits into a C4 envelope (229 × 324 mm) with a little space.
A C4 envelope fits into a B4 envelope (250 × 353 mm) if needed.
4. Size Progression.
Like the A and B series, C series sizes are based on halving/doubling along the longer dimension, maintaining the same √2 aspect ratio (1 : √2 ≈ 1 : 1.414).
5. Practical Use
C4 envelope: Unfolded A4 sheets.
C5 envelope: A5 sheets or A4 folded once (to A5 size).
C6 envelope: A6 sheets or A4 folded twice (to A6 size).
DL envelope (110 × 220 mm) is also common but is a different shape, meant for A4 folded into thirds.
6. International Standard.
ISO 216 (paper sizes) and ISO 269 (envelope sizes, now merged with ISO 216) define these to ensure consistency worldwide, except in countries like the US that use their own paper size systems.