Free C Paper Sizes to Pixels Converter
Convert standard ISO C-series envelope dimensions (C0–C10) to digital screen pixels (px) based on PPI / DPI settings
Understanding ISO C Paper Size Conversions
Part of the universal **ISO 216** standard, the C-series is specifically designed for envelopes and mailing packaging. By sharing the identical aspect ratio of **1:√2 (1:1.414)**, it matches A-series layouts perfectly. A standard C4 envelope accommodates a full sheet of flat A4 paper, a C5 envelope fits an A5 sheet (or an A4 folded in half), and a C6 envelope fits an A6 sheet (or an A4 folded in quarters).
The Mathematical Formula
To convert metric C-series paper measurements into pixel dimensions, divide the width and height millimeter values by 25.4 to determine physical inches, and multiply the resulting values by the PPI/DPI target:
Width (PX) = (Width mm ÷ 25.4) × DPI
Height (PX) = (Height mm ÷ 25.4) × DPI
For example, to calculate standard C4 (229 × 324 mm) envelope paper in digital pixels under standard screen density of 96 PPI:
Height: (324 mm ÷ 25.4) × 96 PPI = 1,224.5 px (rounded to 1,225px)
To prepare the identical C4 cover for professional high-quality print publications at 300 DPI:
Height: (324 mm ÷ 25.4) × 300 DPI = 3,826.7 px (rounded to 3,827px)
ISO C Paper Dimensions Reference Table
Compare physical millimeter dimensions and calculated pixels across standard resolution densities:
| ISO Format | Millimeters (mm) | at Web Standard (96 PPI) | at Print Standard (150 DPI) | at High-Res Press (300 DPI) |
|---|---|---|---|---|
| C0 | 917 × 1297 | 3,466 × 4,902 px | 5,415 × 7,659 px | 10,831 × 15,319 px |
| C1 | 648 × 917 | 2,449 × 3,466 px | 3,827 × 5,415 px | 7,654 × 10,831 px |
| C2 | 458 × 648 | 1,731 × 2,449 px | 2,705 × 3,827 px | 5,409 × 7,654 px |
| C3 | 324 × 458 | 1,225 × 1,731 px | 1,913 × 2,705 px | 3,827 × 5,409 px |
| C4 | 229 × 324 | 866 × 1,225 px | 1,352 × 1,913 px | 2,705 × 3,827 px |
| C5 | 162 × 229 | 612 × 866 px | 957 × 1,352 px | 1,913 × 2,705 px |
| C6 | 114 × 162 | 431 × 612 px | 673 × 957 px | 1,346 × 1,913 px |
Designing for Digital Displays vs High-Res Print
When constructing envelope layouts or mailing templates for digital previews, use **96 PPI** to assure physical dimensions translate accurately on digital screens. When configuring physical envelope products or custom offset prints, configure your targets to **300 DPI** to avoid pixelation.
