Toolman

A3 vs A5

A3A5
Millimetres297 × 420148 × 210
Inches11.69 × 16.545.83 × 8.27
Centimetres29.7 × 4214.8 × 21
Aspect ratio1:1.411:1.42
Area1247.4 cm²310.8 cm²

Which is bigger

A3 is 4 times the area of A5. They are 2 steps apart in the A series and each step halves the sheet, so the multiple is two to the power of 2. The number in the name going up while the sheet goes down is why this has to be asked rather than read off.

A3 is 149 mm wider than A5. A3 is 210 mm taller.

Printing one on the other

A A5 page fits inside A3 whole — print it at 100% and you get a 74.5 mm border down each side and 105 mm top and bottom.

You wantSet the print scale toLeaves
A3 artwork on A5 paper49.8%0 × 0.7 mm margin
A5 artwork on A3 paper200%1 × 0 mm margin

These are the numbers for the "custom scale" box in a print dialog. "Fit to page" computes the same thing, but knowing the figure tells you in advance whether the result will look deliberate or accidental.

Why the shapes matter

The proportions differ: A3 is 1:1.41 and A5 is 1:1.42. That difference is why a layout moved between them never quite lines up — scale it to fit one edge and the other is left with 0.7 mm of unwanted margin.

Frequently asked questions

What is the difference between A3 and A5?

A3 is 297 × 420 mm and A5 is 148 × 210 mm. A3 is the larger of the two by 301.4% in area.

Can I print A3 on A5?

Not at full size. Scale it to 49.8% and it fits inside A5 with 0 × 0.7 mm to spare.

Which is bigger, A3 or A5?

A3 — 297 × 420 mm against 148 × 210 mm, which is 301.4% more area.

Related comparisons

A3 in full · A5 in full · All size comparisons · All paper sizes