Paper Size Converter
Compare and convert international paper sizes (ISO A, B, and C series) and US/Canadian sizes (Letter, Legal, Tabloid). All dimensions are given in millimeters and inches.
ISO A Series (Metric)
The ISO A series is used in most of the world. Each size is half the area of the previous size, with an aspect ratio of 1:√2. The base size, A0, has an area of exactly 1 m².
| Size | Width × Height (mm) | Width × Height (in) | Typical use |
|---|---|---|---|
| A0 | 841 × 1189 | 33.11 × 46.81 | Large posters |
| A1 | 594 × 841 | 23.39 × 33.11 | Posters |
| A2 | 420 × 594 | 16.54 × 23.39 | Small posters, diagrams |
| A3 | 297 × 420 | 11.69 × 16.54 | Drawings, spreadsheets |
| A4 | 210 × 297 | 8.27 × 11.69 | Standard letter (most countries) |
| A5 | 148 × 210 | 5.83 × 8.27 | Notebooks, small booklets |
| A6 | 105 × 148 | 4.13 × 5.83 | Postcards |
| A7 | 74 × 105 | 2.91 × 4.13 | Small cards |
| A8 | 52 × 74 | 2.05 × 2.91 | Business cards (metric) |
| A9 | 37 × 52 | 1.46 × 2.05 | Stamps, labels |
| A10 | 26 × 37 | 1.02 × 1.46 | Tiny labels |
ISO B Series
The B series is used for books, envelopes, and posters. B0 is the geometric mean between A0 and A1 (in a 1:√2 progression), with an area of √2 m².
| Size | Width × Height (mm) | Width × Height (in) |
|---|---|---|
| B0 | 1000 × 1414 | 39.37 × 55.67 |
| B1 | 707 × 1000 | 27.83 × 39.37 |
| B2 | 500 × 707 | 19.69 × 27.83 |
| B3 | 353 × 500 | 13.90 × 19.69 |
| B4 | 250 × 353 | 9.84 × 13.90 |
| B5 | 176 × 250 | 6.93 × 9.84 |
| B6 | 125 × 176 | 4.92 × 6.93 |
| B7 | 88 × 125 | 3.46 × 4.92 |
| B8 | 62 × 88 | 2.44 × 3.46 |
ISO C Series (Envelopes)
The C series is designed for envelopes that hold A-series paper.
| Size | Width × Height (mm) | Width × Height (in) | Fits |
|---|---|---|---|
| C0 | 917 × 1297 | 36.10 × 51.06 | A0 flat |
| C1 | 648 × 917 | 25.51 × 36.10 | A1 flat |
| C2 | 458 × 648 | 18.03 × 25.51 | A2 flat |
| C3 | 324 × 458 | 12.76 × 18.03 | A3 flat |
| C4 | 229 × 324 | 9.02 × 12.76 | A4 flat (unfolded) |
| C5 | 162 × 229 | 6.38 × 9.02 | A4 folded once |
| C6 | 114 × 162 | 4.49 × 6.38 | A4 folded twice (A6) |
| C7 | 81 × 114 | 3.19 × 4.49 | A5 folded (DL size range) |
| C8 | 57 × 81 | 2.24 × 3.19 | Small cards |
| C10 | 28 × 40 | 1.10 × 1.57 | Very small envelopes |
Note: the common "DL" envelope (110 × 220 mm) is not part of the C series, but fits A4 paper folded into thirds. It is the standard business envelope in many countries.
US and Canadian Sizes
US and Canadian paper sizes are based on the US Letter standard and do not follow the ISO ratio. Canadian paper is a hybrid, using US names for ISO A formats (e.g., "Letter" = A4).
| Name | Width × Height (in) | Width × Height (mm) | Typical use |
|---|---|---|---|
| Letter | 8.5 × 11 | 215.9 × 279.4 | Standard US documents |
| Legal | 8.5 × 14 | 215.9 × 355.6 | Legal documents |
| Tabloid / Ledger | 11 × 17 | 279.4 × 431.8 | Posters, drawings |
| Junior Legal | 5 × 8 | 127 × 203.2 | Small legal pads |
| Half Letter | 5.5 × 8.5 | 139.7 × 215.9 | Small notebooks |
| Government Letter | 8 × 10.5 | 203.2 × 266.7 | Old government documents |
| Executive | 7.25 × 10.5 | 184.15 × 266.7 | Executive stationery |
| Statement / Queen | 5.5 × 8.5 | 139.7 × 215.9 | Statement billing |
Comparing A4 and US Letter
The two most common document sizes in the world are:
- A4: 210 × 297 mm (8.27 × 11.69 inches), area = 0.06237 m²
- US Letter: 8.5 × 11 inches (215.9 × 279.4 mm), area = 0.06032 m²
A4 is slightly narrower and taller than Letter. Letter has a slightly smaller area (about 3% smaller).
Because of the different aspect ratios, a document formatted for one size does not fit perfectly on the other without margins or scaling being adjusted. Most printers and word processors handle this automatically.
Real-World Uses
- Printing and photocopying: Most paper sizes are chosen to fit standard printer trays. A4 and Letter are the most common.
- Envelopes and mail: Envelope sizes are matched to the paper they must hold. C-series envelopes fit corresponding A-series paper.
- Posters and graphics: A0–A2 are common for posters; B-series sizes are used for books and larger prints.
- Drawing and design: Engineering drawings use A3 or larger; architectural drawings use A1 or A0.
- Books: Book trim sizes are usually based on ISO or US book industry standards, which are similar to A5 and B-format.
Related Converters
Frequently Asked Questions
What is A4 paper size in inches?
A4 is 210 × 297 mm, which equals approximately 8.27 × 11.69 inches.
What is the difference between A4 and US Letter?
A4 is 210 × 297 mm (8.27 × 11.69 in). US Letter is 8.5 × 11 in (215.9 × 279.4 mm). A4 is narrower and taller; Letter is wider and shorter.
What size is a DL envelope?
DL (Dimension Lengthwise) is 110 × 220 mm (4.33 × 8.66 in). It fits A4 paper folded into thirds and is the standard business envelope in the UK and Europe.
What is the aspect ratio of A-series paper?
The A-series has an aspect ratio of 1:√2 (about 1:1.414). This means folding an A-size sheet in half produces the next size down with the same ratio.
What is the largest ISO paper size?
The 4A0 size (1682 × 2378 mm) is technically the largest defined ISO A-series size, though it is rarely produced. A0 is the practical largest common size.
Are US paper sizes metricated?
US paper sizes are defined in inches and remain in inch-based dimensions. Metric equivalents are used only for reference, not as primary definitions.