ISO C series (envelopes)
C1 envelope size
C1 envelope measures 648 x 917 mm (25.51 x 36.1 in). Part of the ISO C series (envelopes).
648 x 917millimetres
25.51 x 36.1inches
7,654 x 10,831pixels @ 300 dpi
Dimensions in every unit
| Unit | Width x height |
|---|---|
| Millimetres | 648 x 917 mm |
| Centimetres | 64.8 x 91.7 cm |
| Inches (decimal) | 25.512 x 36.102 in |
| Inches (fraction) | 25 1/2 x 36 1/8 in |
| Points (1/72 in) | 1836.9 x 2599.4 pt |
| Picas | 153.07 x 216.61 pc |
Pixel dimensions by resolution
| Resolution | Pixels | Megapixels |
|---|---|---|
| 72 dpi | 1,837 x 2,599 px | 4.8 MP |
| 96 dpi | 2,449 x 3,466 px | 8.5 MP |
| 150 dpi | 3,827 x 5,415 px | 20.7 MP |
| 200 dpi | 5,102 x 7,220 px | 36.8 MP |
| 300 dpi | 7,654 x 10,831 px | 82.9 MP |
| 600 dpi | 15,307 x 21,661 px | 331.6 MP |
300 dpi is the usual target for printed photos and artwork; 72–96 dpi is screen resolution.
Document size with bleed
| Bleed | Millimetres | Inches |
|---|---|---|
| 3 mm bleed (each side) | 654 x 923 mm | 25.748 x 36.339 in |
| 0.125 in bleed (each side) | 654.4 x 923.4 mm | 25.762 x 36.352 in |
How many C1 envelope fit on a press sheet
| Sheet | Without bleed | With 3 mm bleed |
|---|---|---|
| B1 (offset) | 1-up | 1-up |
Simple grid imposition with no gutters or gripper margin; real layouts may fit fewer.
The √2 system
C1 envelope has an aspect ratio of 1 : 1.4151 — close to √2 (1.4142). Folding or cutting it in half across the long side produces the next smaller size in the series with the same proportions, and two sheets side by side form the next larger size. This is why scaling between sizes in the series (for example on a photocopier) never crops or distorts the page.
Similar sizes
Frequently asked questions
What are the dimensions of C1 envelope?
C1 envelope is 648 x 917 mm, which is 25.51 x 36.1 in (25 1/2 x 36 1/8 in).
How many pixels is C1 envelope at 300 DPI?
7,654 x 10,831 pixels at 300 dpi, or 3,827 x 5,415 at 150 dpi.
Sources & data
- Dimensions per the relevant standard; see sources.