📄Paper Sizes

About this tool

Search or scroll through 65 paper, photo, card and envelope sizes, switch units between millimetres, centimetres, inches, points and pixels at any DPI, and flip to landscape. Click a row to compare that size with A4 in a drawing to scale, or copy its dimensions.

How paper sizes work

Most of the world uses the ISO 216 system, which is built on a neat idea. A0 has an area of one square metre and sides in the ratio 1 : √2, and each smaller size is made by cutting the previous one in half across its long side. Because the ratio stays the same, any A size scales to any other without cropping, which is why you can enlarge A4 to A3 on a photocopier. A4 is 210 × 297 mm, A5 is 148 × 210 mm, and A3 is 297 × 420 mm. The B series sits between A sizes and is used for posters and passports, while the C series fits A sizes for envelopes: a C4 envelope holds flat A4, and a C5 holds A4 folded once. The US and Canada use inch-based sizes instead. Letter (8.5 × 11 in, 215.9 × 279.4 mm) is slightly wider and shorter than A4, Legal is 8.5 × 14 in, and Tabloid or Ledger is 11 × 17 in. Engineering and architecture use the ANSI and Arch series. For screens and design apps, sizes are given in points (1/72 inch, used by PDFs) or in pixels at a chosen DPI: A4 at 300 DPI is 2480 × 3508 px, and at 96 DPI it's 794 × 1123 px. Honest limits: photo, card and envelope sizes vary a little between countries and printers, and print shops often need extra bleed (usually 3 mm) around the trim size. The DPI calculator, the image DPI changer and the unit converter are related, and What DPI you actually need for printing covers print resolution.

Frequently asked questions