2026-03-20

The Ultimate Guide to Paper Sizes: A, B, C, and US Standards

Paper size names look arbitrary until you see the two families: ISO (A/B/C) and North American inch sizes. Mix them in one PDF and something always crops.

ISO A, B, and C

A is the everyday series. A4 is the workhorse. Adjacent sizes double in area and keep a √2 ratio, so A3 is two A4s, A5 is half of A4.

B sits between A sizes (B5 notebooks, B4 exams in some countries). C is for envelopes: C4 holds an unfolded A4, C5 holds A5 or a folded A4.

Pixel counts at 300 DPI, millimeters, and inches are all on the paper size chart.

US sizes you’ll actually meet

• Letter — 8.5 × 11 in. Default in the US and Canada.
• Legal — 8.5 × 14 in. Contracts and court packs.
• Tabloid / Ledger — 11 × 17 in. Newsletters, small posters.
• Executive — 7.25 × 10.5 in. Less common, still in some trays.

A4 vs Letter is the trap that bites travelers and remote teams. Details: A4 paper size explained.

What to choose in the generator

Match the tray, not the file you wish you had. Then print lined, graph, or Cornell notes at that size. Custom width/height is there for odd stock, not as a substitute for picking Letter when that’s what’s loaded.

Related tool:Open the full size chart →