C4 Envelope Size
C4 measures 229 × 324 mm (9.02 × 12.76 in). It is the ISO C envelope that holds an unfolded A4 sheet, sitting between A4 and B4, and one of the most used large envelopes in offices.
C4 measures 229 millimetres wide and 324 millimetres tall.
C4 Dimensions in Each Unit
C4 is 229 × 324 mm, which is 22.9 × 32.4 cm or 9.02 × 12.76 in. It is C3 cut in half.
| Unit | Width | Height | Width × height | Copy |
|---|---|---|---|---|
| Millimetres (mm) | 229 | 324 | 229 × 324 mm | |
| Centimetres (cm) | 22.9 | 32.4 | 22.9 × 32.4 cm | |
| Metres (m) | 0.229 | 0.324 | 0.229 × 0.324 m | |
| Inches (in) | 9.02 | 12.76 | 9.02 × 12.76 in | |
| Feet (ft) | 0.75 | 1.06 | 0.75 × 1.06 ft | |
| Points (pt) | 649 | 918 | 649 × 918 pt | |
| Picas (pc) | 54.1 | 76.5 | 54.1 × 76.5 pc | |
| Pixels at 72 DPI | 649 | 918 | 649 × 918 px | |
| Pixels at 150 DPI | 1352 | 1913 | 1352 × 1913 px | |
| Pixels at 300 DPI | 2705 | 3827 | 2705 × 3827 px | |
| Pixels at 600 DPI | 5409 | 7654 | 5409 × 7654 px |
Pixel counts follow from the resolution: pixels = millimetres ÷ 25.4 × DPI. More on the DPI and pixels page.
C4 Shape and Area
| Aspect ratio | 1 : 1.415 (√2) |
|---|---|
| Area | 0.0742 m² · 74,196 mm² |
| Diagonal | 396.8 mm · 15.62 in |
| ISO 216 tolerance | ± 2 mm each side |
| Governing standard | ISO 216:2007 |
C4 to Scale
C4 is half of C3 and folds in half to C5. Put C4 next to another size in the comparison tool.
Frequently Asked Questions
What size is a C4 envelope?
C4 is 229 by 324 mm, or 9.02 by 12.76 inches. It holds an unfolded A4 sheet.
Does C4 fit A4 paper?
Yes, flat and unfolded, with a small clearance. An A3 sheet folded once in half also fits C4.
What is the difference between C4 and C5?
C4 holds A4 unfolded. C5 is half the size and holds A4 folded once or A5 flat.
Which is bigger, C3 or C4?
C3 is the bigger of the two, at 324 × 458 mm against 229 × 324 mm for C4. It has twice the area, so two C4 envelopes cover one C3.
Envelope Sizes
✓ Dimensions per ISO 216:2007; unit values derived by formula. Reviewed . Editorial Process →