C1 Envelope Size
C1 measures 648 × 917 mm (25.51 × 36.10 in). It is the ISO C envelope for an unfolded A1 sheet, half a C0, sitting between A1 and B1.
C1 measures 648 millimetres wide and 917 millimetres tall.
C1 Dimensions in Each Unit
C1 is 648 × 917 mm, which is 64.8 × 91.7 cm or 25.51 × 36.1 in. It is C0 cut in half.
| Unit | Width | Height | Width × height | Copy |
|---|---|---|---|---|
| Millimetres (mm) | 648 | 917 | 648 × 917 mm | |
| Centimetres (cm) | 64.8 | 91.7 | 64.8 × 91.7 cm | |
| Metres (m) | 0.648 | 0.917 | 0.648 × 0.917 m | |
| Inches (in) | 25.51 | 36.1 | 25.51 × 36.1 in | |
| Feet (ft) | 2.13 | 3.01 | 2.13 × 3.01 ft | |
| Points (pt) | 1837 | 2599 | 1837 × 2599 pt | |
| Picas (pc) | 153.1 | 216.6 | 153.1 × 216.6 pc | |
| Pixels at 72 DPI | 1837 | 2599 | 1837 × 2599 px | |
| Pixels at 150 DPI | 3827 | 5415 | 3827 × 5415 px | |
| Pixels at 300 DPI | 7654 | 10831 | 7654 × 10831 px | |
| Pixels at 600 DPI | 15307 | 21661 | 15307 × 21661 px |
Pixel counts follow from the resolution: pixels = millimetres ÷ 25.4 × DPI. More on the DPI and pixels page.
C1 Shape and Area
| Aspect ratio | 1 : 1.415 (√2) |
|---|---|
| Area | 0.594 m² · 594,216 mm² |
| Diagonal | 1122.9 mm · 44.21 in |
| ISO 216 tolerance | ± 3 mm each side |
| Governing standard | ISO 216:2007 |
C1 to Scale
C1 is half of C0 and folds in half to C2. Put C1 next to another size in the comparison tool.
Frequently Asked Questions
What size is a C1 envelope?
C1 is 648 by 917 mm, or 25.51 by 36.10 inches, sized for an unfolded A1 sheet.
What fits in a C1 envelope?
An A1 plan, poster or print, flat and unfolded.
Which is bigger, C0 or C1?
C0 is the bigger of the two, at 917 × 1297 mm against 648 × 917 mm for C1. It has twice the area, so two C1 envelopes cover one C0.
Envelope Sizes
✓ Dimensions per ISO 216:2007; unit values derived by formula. Reviewed . Editorial Process →