Scaling factor: A4 to A3 and every copy percentage
To enlarge A4 to A3, use 141 %. To reduce A3 to A4, use 71 %. Every step in the A series is a factor of √2. The calculator gives the value for any combination, including between ISO and US sizes.
Contents of this page
The scaling table from A0 to A10
Find the size of your original in the row and the target size in the column. Enlargements are highlighted. Many people print this table and pin it up next to the copier.
| from \ to | A0 | A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8 | A9 | A10 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| A0 | 100 % | 71 % | 50 % | 35 % | 25 % | 18 % | 12 % | 8.8 % | 6.2 % | 4.4 % | 3.1 % |
| A1 | 141 % | 100 % | 71 % | 50 % | 35 % | 25 % | 18 % | 12 % | 8.8 % | 6.2 % | 4.4 % |
| A2 | 200 % | 141 % | 100 % | 71 % | 50 % | 35 % | 25 % | 18 % | 12 % | 8.8 % | 6.2 % |
| A3 | 283 % | 200 % | 141 % | 100 % | 71 % | 50 % | 35 % | 25 % | 18 % | 12 % | 8.8 % |
| A4 | 400 % | 283 % | 200 % | 141 % | 100 % | 70 % | 50 % | 35 % | 25 % | 18 % | 12 % |
| A5 | 566 % | 400 % | 283 % | 200 % | 141 % | 100 % | 70 % | 50 % | 35 % | 25 % | 18 % |
| A6 | 801 % | 566 % | 400 % | 283 % | 200 % | 141 % | 100 % | 70 % | 50 % | 35 % | 25 % |
| A7 | 1132 % | 801 % | 566 % | 400 % | 283 % | 200 % | 141 % | 100 % | 70 % | 50 % | 35 % |
| A8 | 1607 % | 1136 % | 803 % | 568 % | 401 % | 284 % | 200 % | 142 % | 100 % | 70 % | 50 % |
| A9 | 2273 % | 1605 % | 1135 % | 803 % | 568 % | 400 % | 284 % | 200 % | 141 % | 100 % | 70 % |
| A10 | 3214 % | 2273 % | 1605 % | 1135 % | 803 % | 568 % | 400 % | 284 % | 200 % | 141 % | 100 % |
Why you only need two values
Because all A sizes share the same aspect ratio, each step up is exactly √2 times as long (141 %) and each step down exactly 1/√2 times (71 %). Over two steps that gives 200 % or 50 %. That is why most copiers offer exactly these values as presets.
Between ISO and US sizes
There is no lossless factor between A4 and Letter, because the aspect ratios differ. To go from A4 to Letter, reduce to 94 % so nothing is cut off. That leaves a narrow margin at the sides. From Letter to A4 it is 97 %, with a strip left at the bottom. The calculator above shows the exact values if you pick Letter as the target, for example.
Frequently asked questions
What percentage is A4 to A3?
141 %.
What percentage is A3 to A4?
71 %.
What percentage is A4 to A5?
71 %, because A5 is one step smaller than A4.
What percentage is A5 to A3?
200 %, because A5 and A3 are two steps apart.