ISO A · ISO 216
A3 paper size
A large ISO sheet commonly used for posters, diagrams, presentation spreads, and drawings that need more room than A4.
Open in the converterDirect answer
A3 dimensions in every unit
In portrait orientation, width comes first: 297 mm × 420 mm. Rotate the sheet for landscape orientation and the same measurements reverse.
| Unit | Width | Height |
|---|---|---|
| Millimeters | 297 mm | 420 mm |
| Centimeters | 29.7 cm | 42 cm |
| Inches | 11.69 in | 16.54 in |
| Points | 841.9 pt | 1190.6 pt |
Digital artwork
A3 pixel dimensions by DPI
Pixel dimensions depend on output resolution. These values describe the trimmed page only and do not include printer bleed.
| Resolution | Pixel width | Pixel height | Typical use |
|---|---|---|---|
| 72 DPI | 842 px | 1,191 px | Screen preview |
| 96 DPI | 1,123 px | 1,587 px | Screen preview |
| 150 DPI | 1,754 px | 2,480 px | Draft print |
| 300 DPI | 3,508 px | 4,961 px | Quality print |
| 600 DPI | 7,016 px | 9,921 px | High-detail source |
Proportion & comparison
How A3 relates to nearby sizes
A3 has twice the area of A4. Fold an A3 sheet in half parallel to its short edge and each half is A4.
- Portrait ratio
- 1 : 1.4141
- Area
- 0.1247 m²
- Orientation
- 297 × 420 mm
Works well for
Common A3 uses
- Small posters
- Architectural diagrams
- Presentation spreads
- Folded A4 brochures
Check before using
Where it can go wrong
- Printers limited to Letter/A4
- Standard document mailers
- Layouts designed for 11 × 17 inches
Regional & printer note
Will a printer recognize A3?
Standard across most countries that use the ISO A-series. Many office printers need a dedicated A3 tray or wide-format feed.
Always match the document size, print-driver size, paper tray, and physical sheet. A driver can silently scale a page even when the preview looks correct.
Measurement source
Checked against the defining standard
Paper Size Lab converts the stored millimeter measurements mathematically; it does not round-trip between units. The underlying sheet family is referenced to the standards organization below.
Read ISO 216:2007Questions people ask
A3 paper FAQ
What are the dimensions of A3 paper?
A3 measures 297 × 420 millimeters, 29.7 × 42 centimeters, or 11.69 × 16.54 inches in portrait orientation.
How many pixels is A3 at 300 DPI?
A3 is 3508 × 4961 pixels at 300 DPI before adding bleed.
Is A3 the same as another paper size?
A3 has twice the area of A4. Fold an A3 sheet in half parallel to its short edge and each half is A4.
What is A3 commonly used for?
A3 is commonly used for small posters, architectural diagrams, presentation spreads, folded a4 brochures. Printer, postal, and finishing requirements still vary.