Paper Size Converter
Paper sizes look arbitrary until you know the rule: each A size is the previous size folded in half, and the proportions stay the same at one to the square root of two. That is why an A4 sheet folded in half is exactly A5. This converter gives every size in millimetres and inches, and shows what each one halves into.
Convert a measurement
Enter your own figure, pick the units on each side, and the result is worked out as you go. Nothing is stored.
All units at once
The same quantity written every way this page knows, so you do not have to convert twice.
Nothing entered yet, so the table below starts from the closest row of the chart.
| Unit | Value |
|---|---|
| A0 | 1 |
| A1 | 1 |
| A2 | 1 |
| A3 | 1 |
| A4 Starting value | 1 |
| A5 | 1 |
| A6 | 1 |
| A7 | 1 |
| A8 | 1 |
| B4 | 1 |
| B5 | 1 |
| US Letter | 1 |
| US Legal | 1 |
| US Tabloid | 1 |
| DL envelope | 1 |
Full size chart
Every size in the standard, printed in full. Read across a row to translate one size into the other systems, or find the measurement you took and take the names beside it.
| Size | Millimetres | Inches |
|---|---|---|
| A0 | 841 x 1189 | 33.1 x 46.8 |
| A1 | 594 x 841 | 23.4 x 33.1 |
| A2 | 420 x 594 | 16.5 x 23.4 |
| A3 | 297 x 420 | 11.7 x 16.5 |
| A4 | 210 x 297 | 8.3 x 11.7 |
| A5 | 148 x 210 | 5.8 x 8.3 |
| A6 | 105 x 148 | 4.1 x 5.8 |
| A7 | 74 x 105 | 2.9 x 4.1 |
| A8 | 52 x 74 | 2.0 x 2.9 |
| B4 | 250 x 353 | 9.8 x 13.9 |
| B5 | 176 x 250 | 6.9 x 9.8 |
| US Letter | 216 x 279 | 8.5 x 11.0 |
| US Legal | 216 x 356 | 8.5 x 14.0 |
| US Tabloid | 279 x 432 | 11.0 x 17.0 |
| DL envelope | 110 x 220 | 4.3 x 8.7 |
What this assumes
- The A series is defined so that each size is half the area of the one before, with the same aspect ratio of one to the square root of two.
- A4 is the standard office size almost everywhere except North America, where US Letter is used. Letter is about 6 millimetres wider and 18 millimetres shorter than A4, which is why A4 documents do not print correctly on Letter paper without scaling.
- A DL envelope takes an A4 sheet folded into three, which is why it is the standard business envelope in A4 countries.
Every figure on this page is worked out from millimetres, and the page states the factor rather than hiding it.
Questions people ask
Is A4 the same as US Letter?
No. A4 is 210 by 297 millimetres, and US Letter is 216 by 279 millimetres. Letter is slightly wider and noticeably shorter, so an A4 document printed on Letter needs scaling down, and a Letter document printed on A4 leaves a wider bottom margin.
What is A4 in inches?
About 8.27 by 11.69 inches. That is a little narrower and a little taller than US Letter, which is why the two are not interchangeable without adjustment.
Which envelope fits an A4 sheet?
A DL envelope at 110 by 220 millimetres takes an A4 sheet folded in three. For a card that is not folded, use a C4 envelope, which takes A4 flat.
What size is A5 in inches?
About 5.83 by 8.27 inches. A5 is exactly half an A4 sheet, which makes it the usual size for a folded greeting card or a small booklet insert.