ARCH A paper size
228.6 × 304.8 mm
9 × 12 inches · 22.86 × 30.48 cm · aspect ratio 1:1.33
What ARCH A is for
ARCH A is 9 × 12 inches, the smallest sheet in the US architectural series, and it is where detail sketches, door and window schedules and single-room enlargements are issued. Its 3:4 proportion is the one the whole series is built on, which is why architects adopted it over ANSI: ANSI sizes come from doubling Letter and therefore alternate between two shapes, while every ARCH sheet reduces to another ARCH sheet without distortion. In practice ARCH A is the quarter-size print of an ARCH C sheet, small enough to staple into a specification binder and still readable at a 1/4-inch scale.
ARCH A in every unit
| Unit | Width | Height |
|---|---|---|
| Millimetres | 228.6 mm | 304.8 mm |
| Centimetres | 22.86 cm | 30.48 cm |
| Inches | 9 in | 12 in |
| Points (PostScript) | 648 pt | 864 pt |
ARCH A in pixels
Pixel dimensions depend entirely on the resolution you are working at — there is no single "pixel size" for a sheet of paper.
| Resolution | Pixels | Use |
|---|---|---|
| 72 DPI | 648 × 864 | Screen preview only — far too coarse to print |
| 150 DPI | 1350 × 1800 | Draft printing, internal documents |
| 300 DPI | 2700 × 3600 | The standard for commercial print |
| 600 DPI | 5400 × 7200 | Fine detail, line art, archival scanning |
Setting up a print document? Use 300 DPI and add 3 mm of bleed on every edge unless your printer specifies otherwise.
How ARCH A relates to the rest of the series
About ARCH A
The smallest architectural sheet at 9 × 12 inches.
Other Architectural sizes
| Size | Millimetres | Inches |
|---|---|---|
| ARCH B | 304.8 × 457.2 mm | 12 × 18 in |
| ARCH C | 457.2 × 609.6 mm | 18 × 24 in |
| ARCH D | 609.6 × 914.4 mm | 24 × 36 in |
| ARCH E | 914.4 × 1219.2 mm | 36 × 48 in |
| ARCH E1 | 762 × 1066.8 mm | 30 × 42 in |
Frequently asked questions
What size is ARCH A in mm?
228.6 × 304.8 mm.
What size is ARCH A in inches?
9 × 12 inches.
What size is ARCH A in pixels?
There is no single answer — it depends on resolution. At the print standard of 300 DPI it is 2700 × 3600 pixels; at 72 DPI it is only 648 × 864.