C4 envelope size in mm, cm and inches
C4 envelope is 229 × 324 mm (9.02 × 12.76 inches).
C4 envelope dimensions
| Unit | Width | Length |
|---|---|---|
| Millimetres | 229 mm | 324 mm |
| Centimetres | 22.9 cm | 32.4 cm |
| Inches | 9.02 in | 12.76 in |
| Points (1/72 in) | 649 | 918 |
Shape: length is 1.415 times the width.
C4 is the envelope for A4 sheets laid flat. It is 19 mm wider and 27 mm longer than A4, which is why folders and stapled documents go in without bending.
What fits in a C4 envelope envelope
The first fold that leaves at least 3 mm to spare each way is shown. “Does not fit” means no fold up to quarters fits.
| Sheet | How it fits | Size when folded | Spare (width, length) |
|---|---|---|---|
| A3 | folded in half | 297 × 210 mm | 19 × 27 mm |
| A4 | flat | 210 × 297 mm | 19 × 27 mm |
| A5 | flat | 148 × 210 mm | 81 × 114 mm |
| A6 | flat | 105 × 148 mm | 124 × 176 mm |
| US Letter | flat | 216 × 279 mm | 13 × 45 mm |
| US Legal | folded in half | 216 × 178 mm | 51 × 108 mm |
| Half Letter (Statement) | flat | 140 × 216 mm | 89 × 108 mm |
Spare is the envelope dimension minus the folded sheet, in mm. Real envelopes vary a little between makers, and a thick insert needs extra room.
C4 and the US 9 × 12 catalog envelope
The US catalog envelope (9 × 12 in, 228.6 × 304.8 mm) is almost the same width as C4 (229 mm) but 19.2 mm shorter. A4 does fit a 9 × 12 envelope flat, but with only 18.6 mm spare across and 7.8 mm along, while a US Letter sheet has 12.7 mm and 25.4 mm to spare. C4 gives A4 more room: 19 mm across and 27 mm along.
Bigger sheets
A3 folded in half becomes A4 (210 × 297 mm) and fits a C4 envelope; flat A3 needs a C3 envelope, 324 × 458 mm. For a B4 sheet (250 × 353 mm), the ISO E4 envelope (280 × 400 mm) is the match.
Frequently asked questions
What size is a C4 envelope in cm?
A C4 envelope is 22.9 x 32.4 cm.
What size is a C4 envelope in inches?
A C4 envelope is 9.02 x 12.76 inches.
Does A4 fit in a C4 envelope?
Yes, flat and unfolded, with 19 mm spare across and 27 mm along.
Does A3 fit in a C4 envelope?
Folded once, yes: A3 folded in half is A4. Flat A3 needs a C3 envelope.
Is a C4 envelope bigger than a US 9 x 12?
They are similar. C4 is 229 x 324 mm; the US 9 x 12 in catalog envelope is 228.6 x 304.8 mm, 19 mm shorter.