A3 size
in mm, inches and pixels.
A3 paper is 297 × 420 mm (29.7 × 42 cm, 11.69 × 16.54 in), twice the size of A4. In pixels, A3 is 3508 × 4961 px at 300 DPI and 1754 × 2480 px at 150 DPI.
Updated
All sizes at a glance
A3 is two A4 pages side by side: the size for posters, drawings and anything that needs more room than a letter.
| Use | Size | Ratio |
|---|---|---|
| Portrait (recommended) | 297 × 420 mm | 1:1.414 (√2) |
| Landscape | 420 × 297 mm | 1.414:1 (√2) |
Pixels at each resolution
The same physical size needs more pixels the sharper you want it. 300 DPI is the usual target for print, 150 DPI for large posters seen from afar.
| Resolution | Pixels | Good for |
|---|---|---|
| 72 DPI | 842 × 1191 px | Screen previews |
| 96 DPI | 1123 × 1587 px | Web and office documents |
| 150 DPI | 1754 × 2480 px | Posters and large prints |
| 300 DPI | 3508 × 4961 px | Print at full quality |
Physical size
| Physical size | Size |
|---|---|
| Millimetres | 297 × 420 mm |
| Centimetres | 29.7 × 42 cm |
| Inches | 11.69 × 16.54 in |
Limits and safe zone
- Standard
- ISO 216, A series
- Area
- 1/8 m², two A4 sheets
- Tolerance (ISO 216)
- ±2 mm on each side
Semurai Canvas
Design it in Semurai Canvas
Start at the exact size, from a template or a blank page, and apply your Brand Kit: logo, colours and fonts. The AI chat edits the design when you ask.
Create a design, open Resize, choose “Resize this design” and set 3508 × 4961 px (any size from 200 to 6000 px).
After sign-up and a short brand setup, Canvas opens a blank 3508 × 4961 px design.
Already have an account? Open Canvas at 3508 × 4961 px
What A3 is used for
A3 is the go-to size for small posters and noticeboard flyers, drawings and sketches, charts, menus and presentation handouts with large tables.
Folded in half, an A3 sheet gives four A4 pages, which is how many brochures and booklets are printed.
A3 page size in pixels
At 300 DPI, A3 is 3508 × 4961 px. Use it for anything read up close, such as a menu, a drawing or a chart with small labels.
A poster seen from a few steps away is fine at 150 DPI: 1754 × 2480 px. On screen, at 96 DPI, A3 is 1123 × 1587 px.
A3 vs A4
A3 has exactly twice the area of A4 and the same shape. That is why copiers enlarge A4 to A3 at 141%: the √2 ratio scales one into the other without cropping.
Check your printer before you design: many office machines take A3, but many home printers only take sheets up to A4, so A3 often goes to a copy shop or a print shop.
Tips
- Set the size to 3508 × 4961 px before you start: an A4 design scaled up to A3 drops from 300 to about 212 DPI.
- For a landscape A3, swap the numbers: 420 × 297 mm, or 4961 × 3508 px at 300 DPI.
- Keep text at least a few millimetres from the edges if the sheet goes through an office printer.
- Ask the print shop for their bleed and colour requirements before you export.
How to make it in Semurai Canvas
- Create a design in Semurai Canvas, open Resize, choose “Resize this design” and set 3508 × 4961 px, which is A3 at 300 DPI.
- Lay out the page yourself or ask the AI chat to draft it, then adjust text, images and colours.
- Export a PNG or PDF and send it to your printer, after checking their bleed and colour requirements.
FAQ
Questions about this size
How many A4 pages fit on an A3 sheet?
Two, side by side. A3 is 297 × 420 mm and A4 is 210 × 297 mm, so the long side of A4 is the short side of A3.
What is A3 in inches?
A3 is 11.69 × 16.54 in (29.7 × 42 cm). It is close to US Tabloid, 11 × 17 in, but slightly wider and shorter.
What resolution does an A3 poster need?
Use 300 DPI (3508 × 4961 px) if people read it up close. For a poster seen from a few steps away, 150 DPI (1754 × 2480 px) is enough and keeps the file small.
The right size,
on brand from the start.
Semurai plans, writes and designs with you. In Canvas you start at the size you need.
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