C3 Envelope Size
C3 measures 324 × 458 mm (12.76 × 18.03 in). It is the ISO C envelope for an unfolded A3 sheet, an eighth of C0, sitting between A3 and B3.
C3 measures 324 millimetres wide and 458 millimetres tall.
C3 Dimensions in Each Unit
C3 is 324 × 458 mm, which is 32.4 × 45.8 cm or 12.76 × 18.03 in. It is C2 cut in half.
| Unit | Width | Height | Width × height | Copy |
|---|---|---|---|---|
| Millimetres (mm) | 324 | 458 | 324 × 458 mm | |
| Centimetres (cm) | 32.4 | 45.8 | 32.4 × 45.8 cm | |
| Metres (m) | 0.324 | 0.458 | 0.324 × 0.458 m | |
| Inches (in) | 12.76 | 18.03 | 12.76 × 18.03 in | |
| Feet (ft) | 1.06 | 1.5 | 1.06 × 1.5 ft | |
| Points (pt) | 918 | 1298 | 918 × 1298 pt | |
| Picas (pc) | 76.5 | 108.2 | 76.5 × 108.2 pc | |
| Pixels at 72 DPI | 918 | 1298 | 918 × 1298 px | |
| Pixels at 150 DPI | 1913 | 2705 | 1913 × 2705 px | |
| Pixels at 300 DPI | 3827 | 5409 | 3827 × 5409 px | |
| Pixels at 600 DPI | 7654 | 10819 | 7654 × 10819 px |
Pixel counts follow from the resolution: pixels = millimetres ÷ 25.4 × DPI. More on the DPI and pixels page.
C3 Shape and Area
| Aspect ratio | 1 : 1.414 (√2) |
|---|---|
| Area | 0.148 m² · 148,392 mm² |
| Diagonal | 561 mm · 22.09 in |
| ISO 216 tolerance | ± 2 mm each side |
| Governing standard | ISO 216:2007 |
C3 to Scale
C3 is half of C2 and folds in half to C4. Put C3 next to another size in the comparison tool.
Frequently Asked Questions
What size is a C3 envelope?
C3 is 324 by 458 mm, or 12.76 by 18.03 inches, sized for an unfolded A3 sheet.
What fits in a C3 envelope?
An A3 sheet flat, an A2 sheet folded once, or a thick bundle of A4 pages that must stay unfolded.
Which is bigger, C2 or C3?
C2 is the bigger of the two, at 458 × 648 mm against 324 × 458 mm for C3. It has twice the area, so two C3 envelopes cover one C2.
Envelope Sizes
✓ Dimensions per ISO 216:2007; unit values derived by formula. Reviewed . Editorial Process →