A3 vs A4
A3 is two A4 pages side by side, 297 × 420 mm against 210 × 297. One fold turns A3 into A4; a copier does the same at 71%, and A4 back to A3 at 141%, with nothing cropped.
Compare a Different Pair
A3 and A4, Side by Side
| A3 | A4 | Difference | |
|---|---|---|---|
| Millimetres | 297 × 420 | 210 × 297 | 87 × 123 mm |
| Inches | 11.69 × 16.54 | 8.27 × 11.69 | 3.43 × 4.84 in |
| Centimetres | 29.7 × 42.0 | 21.0 × 29.7 | |
| Area | 0.125 m², 124,740 mm² | 0.0624 m², 62,370 mm² | 2× |
| Aspect ratio | 1 : 1.414 (√2) | 1 : 1.414 (√2) | same |
What Is Lost Printing One on the Other
At 100% scale, both centred, nothing resized. A positive figure on the wider or taller side is cropped; on the other it is a blank margin.
| Axis | Gap | A3 onto A4 | A4 onto A3 |
|---|---|---|---|
| Width | 43.5 mm (1.71 in) each side | A3 loses it | blank band |
| Height | 61.5 mm (2.42 in) each end | A3 loses it | blank band |
Scale-to-Fit Percentages
The figure to type into a printer or PDF dialog to scale one to fit inside the other:
| A4 to fit A3 | 141% | fills the sheet, nothing cropped |
|---|---|---|
| A3 to fit A4 | 71% | fills the sheet, nothing cropped |
Both are one halving apart on the 1 : √2 series, so these are the copier presets and nothing is distorted or lost.
Which Should You Use?
A4 for anything that has to go through a normal office printer. A3 when a table, drawing or spread genuinely needs the width and can fold back to A4 for filing.
Beyond the Measurements
Envelopes: A3 fits C3; A4 fits C4, C5, DL.
Worth Knowing
The temptation with A3 is to reach for it whenever A4 feels tight, then discover the office printer only does A4 and the document lives its life folded in a drawer. A3 earns its place when the width is doing real work: a wide spreadsheet, a set of accounts, a plan, a menu that opens out. If the content would survive being set in two columns on A4, it probably should be. If it would not, A3 is the right call and the folding is a fair price.
Frequently Asked Questions
Is A3 bigger than A4?
A3 is bigger. It is 297 × 420 mm against 210 × 297 mm for A4, about 2 times the area.
What is the difference between A3 and A4?
A3 is two A4 pages side by side, 297 × 420 mm against 210 × 297. One fold turns A3 into A4; a copier does the same at 71%, and A4 back to A3 at 141%, with nothing cropped.
Can you print A4 on A3?
Yes, cleanly. Set the printer to scale A4 to 141% and it fills A3 edge to edge with nothing lost.
✓ Dimensions per the standards on the A3 and A4 pages. Differences and scale factors computed. Reviewed . Editorial Process →