What is the difference between A4 and US Letter?

A4 is 210 × 297mm (8.27 × 11.69in), used almost everywhere outside North America. US Letter is 216 × 279mm (8.5 × 11in), used in the United States and Canada. Letter is slightly wider and shorter than A4.

How do A-series paper sizes relate to each other?

Each size is exactly half the area of the one before it, folded along its long edge — two A5 sheets make one A4 sheet, two A4 sheets make one A3 sheet, and so on.

Paper Size Converter

Look up standard paper dimensions, or convert a custom size between millimeters and inches.

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Standard Paper Sizes

Size	Millimeters	Inches
A0	841 × 1189 mm	33.110236 × 46.811024 in
A1	594 × 841 mm	23.385827 × 33.110236 in
A2	420 × 594 mm	16.535433 × 23.385827 in
A3	297 × 420 mm	11.692913 × 16.535433 in
A4	210 × 297 mm	8.267717 × 11.692913 in
A5	148 × 210 mm	5.826772 × 8.267717 in
A6	105 × 148 mm	4.133858 × 5.826772 in
A7	74 × 105 mm	2.913386 × 4.133858 in
Letter (US)	216 × 279 mm	8.503937 × 10.984252 in
Legal (US)	216 × 356 mm	8.503937 × 14.015748 in
Tabloid (US)	279 × 432 mm	10.984252 × 17.007874 in
Executive (US)	184 × 267 mm	7.244094 × 10.511811 in