A4 vs A3
The exact difference between the two, the scaling percentage to print either one on the other, and the shared safe area if you need a single file that works on both.
Side by side
| A4 | A3 | Difference | |
|---|---|---|---|
| Width (mm) | 210 | 297 | 87 |
| Height (mm) | 297 | 420 | 123 |
| Width (in) | 8.268 | 11.693 | 3.425 |
| Height (in) | 11.693 | 16.535 | 4.842 |
| Aspect ratio | 1:1.414 | 1:1.414 | — |
| Pixels at 300 DPI | 2,480 × 3,508 | 3,508 × 4,961 | — |
| Standard | ISO 216 | ISO 216 | — |
Printing one on the other
Enter that percentage in your printer's scale field. Anything under 100% shrinks the page to fit and leaves an uneven margin — that is expected, and it is the only way to avoid losing content off the edge.
One file that prints on both
If you sell printables, this is the single most useful number on the page. US buyers print on one size and most of the rest of the world prints on the other. Designing to the shared safe area means you ship one file instead of two, and neither audience gets a cut-off edge.
Common questions
What is the difference between A4 and A3?
A3 is 87 mm wider and A3 is 123 mm taller. In full: A4 is 210 × 297 mm and A3 is 297 × 420 mm.
How do I print A4 artwork on A3 paper?
Set the printer scaling to 141.4%. That fits the whole A4 page inside A3 without cropping anything. Choose “fit to page” only if your printer offers it — “actual size” will crop.
How do I print A3 artwork on A4 paper?
Scale to 70.7%.
Can I design one file that prints correctly on both?
Yes. Keep everything that must not be cropped inside 210 × 297 mm (8.27 × 11.69 in), centred. That rectangle fits inside both sizes, so the same PDF prints safely either way. This is the standard trick for selling printables to both US and international buyers.