The numbers
| A4 | US Letter | |
|---|---|---|
| Millimeters | 210 × 297 | 215.9 × 279.4 |
| Inches | 8.27 × 11.69 | 8.5 × 11 |
| Points (1/72 in) | 595 × 842 | 612 × 792 |
| Aspect ratio | 1 : 1.414 (√2) | 1 : 1.294 |
A4 is about 6 mm (0.23 in) narrower and 18 mm (0.69 in) taller than Letter.
Who uses which
Letter is standard in the United States, Canada, Mexico, the Philippines and several Latin American countries. A4 is standard almost everywhere else, including the UK, Europe, Australia, India, China and Japan.
A4 belongs to the ISO 216 series. Every A size has the same √2 proportions, so folding A4 in half gives A5 and two A4 sheets side by side make A3. That makes scaling between A sizes clean, which is not true of Letter and its neighbours (Legal, Tabloid).
Printing one on the other
- A4 file on Letter paper: the page is taller than the paper, so about 9 mm can be cut off at the top and bottom. Choose “Fit to printable area” to shrink it about 6%, or keep “Actual size” if the content has generous margins.
- Letter file on A4 paper: the page is wider than the paper, so a few millimeters can be cut off at the sides. “Fit” shrinks it about 3%.
- Exact grids and rulings: scaling changes line spacing. If spacing must be exact, generate the template in the right size instead of scaling. Every generator on this site has a paper size option.
In practice
Someone in the US downloads a worksheet made for A4, prints it on Letter, and finds the bottom margin missing. The content was designed for a taller sheet. Matching the PDF page size to the paper in the tray avoids scaling, clipped edges and grids that no longer measure correctly.
Common mistakes
| Problem | Usually because | What to do |
|---|---|---|
| The bottom of the page is cut off | A4 PDF printed on Letter at 100% | Choose the matching paper size before printing |
| The grid measures short | “Fit to page” scaled the PDF | Print at Actual size or 100% |
| Margins look uneven | The printer’s unprintable area differs | Leave at least 5 mm safe margin |
Blank PDF
Lined paper
Graph paper