Reference library

C4 Envelope Paper Size

C4 measures 229 x 324 mm, 22.9 x 32.4 cm, or 9.02 x 12.76 in. See pixel dimensions by DPI, aspect ratio, bleed setup, comparisons, and related tools.

Last checked: 2026-05-01

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At a glance

C4 is 229 x 324 mm, 22.9 x 32.4 cm, or 9.02 x 12.76 in. At 300 DPI, C4 is 2705 x 3827 px.

Last checked: 2026-05-01 Source: ISO 269:1985 Found a spec change? Send correction.

How we calculate this

Methodology and source handling

We convert physical sizes to inches, multiply by the selected DPI/PPI value, and round to whole pixels.

Methodology Editorial policy

Quick answer

Copy-ready answer

C4 is 229 x 324 mm, 22.9 x 32.4 cm, or 9.02 x 12.76 in. At 300 DPI, C4 is 2705 x 3827 px.

229 x 324 mm

Dimensions and specs

Millimeters	229 x 324 mm
Centimeters	22.9 x 32.4 cm
Inches	9.02 x 12.76 in
300 DPI pixels	2705 x 3827 px
Aspect ratio	1:1.4148
Standard family	ISO C Envelope Series

Pixels

Pixel dimensions by DPI

DPI / PPI	Width	Height	Use
72 DPI	649 px	918 px	Screen or draft reference density
96 DPI	866 px	1225 px	Screen or draft reference density
150 DPI	1352 px	1913 px	Screen or draft reference density
300 DPI	2705 px	3827 px	Common high-quality print setup
600 DPI	5409 px	7654 px	High-resolution archival or print workflow

Formula

How to calculate this size

Pixel formulapixels = millimeters / 25.4 x PPI

229 mm x 300 PPI = 2,705 px wide.

Trim result2,705 x 3,827 px

Use this when the artwork stops at the finished edge.

Bleed result2,705 x 3,827 px

Add 0 mm per side before calculating pixels when artwork reaches the edge.

Common mistakes

Avoid these c4 envelope paper size problems

Mixing screen pixels with print quality

A paper size needs a PPI target before pixels mean anything for print.

Forgetting orientation

Portrait and landscape use the same dimensions, but width and height swap in the export.

Adding bleed to a paper reference

Paper pages show trim size first; add bleed only when the design prints to the edge.

Calculator

Calculate pixels and bleed

Enter any DPI to calculate the pixel dimensions for this physical size.

Compare

Compare C4 Envelope Paper Size

Open a curated comparison or send both sizes into the compare tool with a fragment URL.

compare tool C4 vs C3

C4 Envelope Paper Size: 229 x 324 mm
C3: 324 x 458 mm

50% smaller than C3 Envelope Paper Size. 0.0006 decimal ratio difference compare tool C4 vs C5

C4 Envelope Paper Size: 229 x 324 mm
C5: 162 x 229 mm

100% larger than C5 Envelope Paper Size. 0.0006 decimal ratio difference compare tool C4 vs A4

C4 Envelope Paper Size: 229 x 324 mm
A4: 210 x 297 mm

19% larger than A4 Paper Size in Pixels, Millimeters, Centimeters and Inches. nearly identical aspect ratio compare tool C4 vs US Letter

C4 Envelope Paper Size: 229 x 324 mm
US Letter: 215.9 x 279.4 mm

23% larger than US Letter Paper Size. 0.0659 decimal ratio difference

C4 belongs to the ISO C Envelope Series family. Use this reference for print setup, document layout, template sizing, pixel conversion, and comparisons with nearby paper sizes. Pixel dimensions are calculated from the physical size and selected DPI.

Workflow

Use C4 Envelope Paper Size in a finished file

Confirm the physical size

Copy the millimeter, centimeter, or inch dimensions for the selected paper standard.

Choose PPI

Use 300 PPI for most sharp print exports, or match the printer requirement.

Calculate pixels

Multiply inches by PPI, then add bleed only when artwork reaches the trimmed edge.

Related pages and tools

same series C3 paper size same series C5 paper size common alternative A4 paper size common alternative US Letter paper size comparison C4 vs C3 comparison C4 vs C5 tool DPI calculator tool Print bleed calculator tool Compare sizes tool

Same branch

Nearby pages

A4 Paper Size in Pixels, Millimeters, Centimeters and Inches A5 Paper Size Legal Paper Size US Letter Paper Size A0 Paper Size A1 Paper Size A10 Paper Size A2 Paper Size

FAQ

Common questions

What is the exact C4 size?

C4 measures 229 x 324 mm, 22.9 x 32.4 cm, or approximately 9.02 x 12.76 in.

What is C4 in pixels at 300 DPI?

C4 at 300 DPI is 2705 x 3827 px when rounded to the nearest whole pixel.

What aspect ratio is C4?

C4 has an aspect ratio of about 1:1.4148 based on its 229 x 324 mm physical dimensions.

Should I add bleed to a C4 design?

Envelope print workflows vary by provider and production method. Confirm bleed, flap, and safe-area requirements with the printer or envelope template before output.

References

Sources and references

ISO 269 physical dimensions. Pixel values are calculated from millimeters / 25.4 x DPI and rounded to whole pixels.

ISO 269:1985
Used for ISO C envelope dimensions and DL envelope references.
HP paper size reference
Used as a reputable printer reference for North American office, ANSI, and envelope dimensions.
W3C CSS Values and Units Module
Used for CSS unit definitions, absolute unit relationships, and CSS px behavior.

Last checked: 2026-05-01