ISO C series (envelopes)

C9 envelope size

C9 envelope measures 40 x 57 mm (1.57 x 2.24 in). Part of the ISO C series (envelopes).

40 x 57millimetres

1.57 x 2.24inches

472 x 673pixels @ 300 dpi

Dimensions in every unit

Unit	Width x height
Millimetres	40 x 57 mm
Centimetres	4 x 5.7 cm
Inches (decimal)	1.575 x 2.244 in
Inches (fraction)	1 9/16 x 2 1/4 in
Points (1/72 in)	113.4 x 161.6 pt
Picas	9.45 x 13.46 pc

Pixel dimensions by resolution

Resolution	Pixels	Megapixels
72 dpi	113 x 162 px	0 MP
96 dpi	151 x 215 px	0 MP
150 dpi	236 x 337 px	0.1 MP
200 dpi	315 x 449 px	0.1 MP
300 dpi	472 x 673 px	0.3 MP
600 dpi	945 x 1,346 px	1.3 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)	46 x 63 mm	1.811 x 2.48 in
0.125 in bleed (each side)	46.4 x 63.4 mm	1.825 x 2.494 in

How many C9 envelope fit on a press sheet

Sheet	Without bleed	With 3 mm bleed
A4	25-up	18-up
A3	50-up	36-up
SRA3	56-up	45-up
Letter	20-up	18-up
Tabloid 11 x 17 in	42-up	36-up
12 x 18 in	56-up	42-up
13 x 19 in (Super B)	64-up	50-up
B2 (offset)	144-up	110-up
B1 (offset)	300-up	231-up

Simple grid imposition with no gutters or gripper margin; real layouts may fit fewer.

The √2 system

C9 envelope has an aspect ratio of 1 : 1.425 — 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.

Frequently asked questions

What are the dimensions of C9 envelope?

C9 envelope is 40 x 57 mm, which is 1.57 x 2.24 in (1 9/16 x 2 1/4 in).

How many pixels is C9 envelope at 300 DPI?

472 x 673 pixels at 300 dpi, or 236 x 337 at 150 dpi.

Sources & data

Dimensions per the relevant standard; see sources.