A3 Paper Size in mm and Inches
A3 = 297 x 420 mm (11.7 x 16.5 in) under ISO 216. It is exactly twice the area of A4.
Open the interactive Standards & Sizes tool →Key facts
| Millimeters | 297 x 420 mm |
|---|---|
| Inches | 11.7 x 16.5 in |
| Standard | ISO 216, A-series |
| Relation | 2 x A4 |
| Typical use | Drawings, spread documents |
Frequently asked questions
What size is A3 in cm?
A3 is 29.7 x 42.0 cm (297 x 420 mm), or 11.7 x 16.5 inches.
Is A3 double A4?
Yes. A3 (297 x 420 mm) has exactly twice the area of A4 (210 x 297 mm).
Related pages
A3 Paper Size is part of Standards & Sizes on GOAT Lab — a free reference you can use without signing up, and it works offline. Open the tool above for any custom value.
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