ISO C series (envelopes)

C8 envelope size

C8 envelope measures 57 x 81 mm (2.24 x 3.19 in). Part of the ISO C series (envelopes).

57 x 81millimetres

2.24 x 3.19inches

673 x 957pixels @ 300 dpi

Dimensions in every unit

Unit	Width x height
Millimetres	57 x 81 mm
Centimetres	5.7 x 8.1 cm
Inches (decimal)	2.244 x 3.189 in
Inches (fraction)	2 1/4 x 3 3/16 in
Points (1/72 in)	161.6 x 229.6 pt
Picas	13.46 x 19.13 pc

Pixel dimensions by resolution

Resolution	Pixels	Megapixels
72 dpi	162 x 230 px	0 MP
96 dpi	215 x 306 px	0.1 MP
150 dpi	337 x 478 px	0.2 MP
200 dpi	449 x 638 px	0.3 MP
300 dpi	673 x 957 px	0.6 MP
600 dpi	1,346 x 1,913 px	2.6 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)	63 x 87 mm	2.48 x 3.425 in
0.125 in bleed (each side)	63.4 x 87.4 mm	2.494 x 3.439 in

How many C8 envelope fit on a press sheet

Sheet	Without bleed	With 3 mm bleed
A4	10-up	9-up
A3	25-up	18-up
SRA3	25-up	25-up
Letter	9-up	9-up
Tabloid 11 x 17 in	21-up	18-up
12 x 18 in	25-up	21-up
13 x 19 in (Super B)	32-up	25-up
B2 (offset)	72-up	56-up
B1 (offset)	144-up	121-up

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

The √2 system

C8 envelope has an aspect ratio of 1 : 1.4211 — 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 C8 envelope?

C8 envelope is 57 x 81 mm, which is 2.24 x 3.19 in (2 1/4 x 3 3/16 in).

How many pixels is C8 envelope at 300 DPI?

673 x 957 pixels at 300 dpi, or 337 x 478 at 150 dpi.

Sources & data

Dimensions per the relevant standard; see sources.