> PAPER_SIZE_REFERENCE

A-series, Letter/Legal/Tabloid, dimensions in both mm and inches, plus practical print-DPI guidance most size charts leave out.

> ISO A-SERIES

A0841 × 1189 mm (33.1 × 46.8 in)

A1594 × 841 mm (23.4 × 33.1 in)

A2420 × 594 mm (16.5 × 23.4 in)

A3297 × 420 mm (11.7 × 16.5 in)

A4210 × 297 mm (8.3 × 11.7 in)

A5148 × 210 mm (5.8 × 8.3 in)

A6105 × 148 mm (4.1 × 5.8 in)

> NORTH AMERICAN

Letter216 × 279 mm (8.5 × 11 in)

Legal216 × 356 mm (8.5 × 14 in)

Tabloid279 × 432 mm (11 × 17 in)

Statement140 × 216 mm (5.5 × 8.5 in)

> DPI AND MARGINS, THE PART MOST CHARTS SKIP

A dimension alone doesn't tell you what resolution to design at. For print, 300 DPI (dots per inch) is the standard target for anything viewed up close (documents, photos); 150 DPI is usually fine for large-format posters viewed from a distance, since the eye can't resolve the extra detail anyway. At 300 DPI, an A4 page (8.3 × 11.7 in) needs a canvas of roughly 2481 × 3510 pixels; US Letter (8.5 × 11 in) needs roughly 2550 × 3300.

Every A-series size is exactly half the area of the size above it, cut along the long edge (A4 folded in half makes two A5 sheets) - the same aspect ratio (1:√2) is preserved at every step, which is why A-series paper stacks and scales so cleanly and North American sizes don't (Letter and Legal share a width but not the same ratio, and neither shares a ratio with Tabloid).

A safe default print margin is 0.5 in (12.7 mm) on all sides for home/office printers - most consumer printers can't reliably print closer to the edge than that without risk of clipping, regardless of what the page size itself allows.