Paper sizes in mm, cm and inches

Q: What size is A4 in mm?

A4 is 210 × 297 millimetres. That is 21.0 × 29.7 cm, or 8.27 × 11.69 inches.

Q: What size is A4 in cm?

A4 is 21.0 × 29.7 centimetres, which is the same as 210 × 297 mm.

Q: Is A4 the same as US Letter?

No. US Letter is 8.5 × 11 inches (215.9 × 279.4 mm). Compared with A4 it is about 6 mm wider and 18 mm shorter, so the two are not interchangeable. When printing across them, use your printer's fit-to-page setting.

Q: What is the logic behind A paper sizes?

Every A size is the previous one folded in half, and all of them share the same √2 side ratio. That is why scaling A4 to A5 or A3 never distorts the layout. A0 is defined as one square metre in area.

Q: What is the most common paper size?

A4 (210 × 297 mm) is the standard document size everywhere except the United States and Canada, where US Letter (8.5 × 11 in) is standard.

A4 is 210 × 297 mm — that's 21.0 × 29.7 cm, or 8.27 × 11.69 inches. Below is every ISO A-series and B-series size plus the US formats, with a live size finder. Pick a format for its exact dimensions in all three units.

Paper format

A-series B-series US sizes A4 vs Letter FAQ

210 × 297 mmA4 in millimetres

21.0 × 29.7 cmA4 in centimetres

8.27 × 11.69 inA4 in inches

A-series paper sizes (ISO 216)

The A-series is the world's standard. Each size is the previous one cut in half, so two sheets of A4 make an A3, and the √2 ratio means a layout scales between them without distortion. A0 has an area of exactly one square metre.

Format	Millimetres	Centimetres	Inches
A0	841 × 1189 mm	84.1 × 118.9 cm	33.11 × 46.81″
A1	594 × 841 mm	59.4 × 84.1 cm	23.39 × 33.11″
A2	420 × 594 mm	42.0 × 59.4 cm	16.54 × 23.39″
A3	297 × 420 mm	29.7 × 42.0 cm	11.69 × 16.54″
A4	210 × 297 mm	21.0 × 29.7 cm	8.27 × 11.69″
A5	148 × 210 mm	14.8 × 21.0 cm	5.83 × 8.27″
A6	105 × 148 mm	10.5 × 14.8 cm	4.13 × 5.83″
A7	74 × 105 mm	7.4 × 10.5 cm	2.91 × 4.13″
A8	52 × 74 mm	5.2 × 7.4 cm	2.05 × 2.91″
A9	37 × 52 mm	3.7 × 5.2 cm	1.46 × 2.05″
A10	26 × 37 mm	2.6 × 3.7 cm	1.02 × 1.46″

B-series paper sizes (ISO 216)

B-series sizes sit between the A sizes and are used for posters, books and envelopes that need to be a bit larger than the nearest A size.

Format	Millimetres	Centimetres	Inches
B0	1000 × 1414 mm	100.0 × 141.4 cm	39.37 × 55.67″
B1	707 × 1000 mm	70.7 × 100.0 cm	27.83 × 39.37″
B2	500 × 707 mm	50.0 × 70.7 cm	19.69 × 27.83″
B3	353 × 500 mm	35.3 × 50.0 cm	13.90 × 19.69″
B4	250 × 353 mm	25.0 × 35.3 cm	9.84 × 13.90″
B5	176 × 250 mm	17.6 × 25.0 cm	6.93 × 9.84″

US paper sizes

North America uses its own set of formats instead of the ISO sizes. Letter is the everyday document size, the equivalent of A4.

Format	Inches	Millimetres	Centimetres
Letter	8.5 × 11″	215.9 × 279.4 mm	21.6 × 27.9 cm
Legal	8.5 × 14″	215.9 × 355.6 mm	21.6 × 35.6 cm
Tabloid / Ledger	11 × 17″	279.4 × 431.8 mm	27.9 × 43.2 cm
Executive	7.25 × 10.5″	184.2 × 266.7 mm	18.4 × 26.7 cm

A4 vs US Letter

These are the two everyday document sizes, and they're close enough to cause trouble. A4 (210 × 297 mm) is narrower and taller; Letter (215.9 × 279.4 mm) is wider and shorter. The difference is about 6 mm in width and 18 mm in height.

Printing across the two? If you print an A4 document on Letter paper (or the reverse), set your printer to "fit to page" or "scale to fit" — otherwise you'll lose a strip off one edge or get an unwanted margin. For exact layouts (forms, certificates), design for whichever standard your audience uses.

Paper questions

normal paper size · A4 vs Letter · A4 in inches · A4 in pixels · A5 · A3 · A6 · Legal

Photo print sizes

4×6 · 5×7 · 8×10

Related object sizes

business card · passport photo · all common objects

A4 in every unit

A4 in mm · A4 in cm · A4 in inches · A4 in pixels

Frequently asked questions

What size is A4 in mm?

A4 is 210 × 297 millimetres — that's 21.0 × 29.7 cm or 8.27 × 11.69 inches.

What size is A4 in cm?

A4 is 21.0 × 29.7 centimetres, the same as 210 × 297 mm.

What size is A4 in inches?

A4 is 8.27 × 11.69 inches, the same as 210 × 297 mm.

Is A4 the same as US Letter?

No. US Letter is 8.5 × 11 inches (215.9 × 279.4 mm) — about 6 mm wider and 18 mm shorter than A4, so they're not interchangeable. Use "fit to page" when printing across them.

What is the logic behind A paper sizes?

Every A size is the previous one folded in half, and they all share the √2 side ratio, so scaling A4 to A5 or A3 never distorts the layout. A0 is exactly one square metre in area.

What is the most common paper size?

A4 is the standard document size everywhere except the United States and Canada, where US Letter is standard.