What is the most common paper size?

A4 (210 × 297 mm) is the international standard used in most countries. In the US and Canada, Letter (216 × 279 mm) is the standard. A4 is slightly taller and narrower than Letter.

How does the A-series paper sizing work?

Each A-series size is exactly half the previous size when folded along the longer side. A0 has an area of 1 square meter. A1 = A0 folded in half, A2 = A1 folded in half, and so on. The aspect ratio is always 1:√2 (approximately 1:1.414).

What are C-series paper sizes used for?

C-series sizes are designed for envelopes. C4 fits an unfolded A4 sheet, C5 fits A4 folded once, and C6 fits A4 folded twice. The C sizes are between A and B series dimensions.

What is 300 DPI and why does it matter?

DPI (Dots Per Inch) measures print resolution. 300 DPI is the standard for high-quality printing. An A4 page at 300 DPI is 2480 × 3508 pixels. For web/screen use, 72 DPI is common (595 × 842 pixels for A4).

Is this paper size converter free?

Yes, completely free with no registration required. Works on all devices.

Paper Size Converter — Free, Instant · No Sign-Up

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

Select size

inches

841×1189

84.1×118.9

33.11×46.81

594×841

59.4×84.1

23.39×33.11

420×594

42.0×59.4

16.54×23.39

297×420

29.7×42.0

11.69×16.54

210×297

21.0×29.7

8.27×11.69

148×210

14.8×21.0

5.83×8.27

105×148

10.5×14.8

4.13×5.83

74×105

7.4×10.5

2.91×4.13

52×74

5.2×7.4

2.05×2.91

37×52

3.7×5.2

1.46×2.05

A10

26×37

2.6×3.7

1.02×1.46

The Paper Size Converter converts between all standard paper formats — ISO A series (A0 through A10), B series, C series (envelope sizes), North American Letter, Legal, Ledger and Tabloid sizes — displaying dimensions in both millimetres and inches. Understanding paper size standards is essential for graphic designers, print professionals, office administrators and anyone who works with international documents, packaging or printing specifications.

The ISO 216 standard (adopted by all countries except the United States and Canada) defines the A series: A0 has an area of exactly one square metre, and each subsequent size is created by halving the longer dimension. A4 (210 x 297 mm) is the most widely used paper size globally. North American Letter (215.9 x 279.4 mm, or 8.5 x 11 inches) is slightly wider and shorter than A4. Legal (215.9 x 355.6 mm) is longer than Letter. When designing documents for international distribution, A4 and Letter are the primary formats to support — most modern word processors include templates for both.

For printing professionals, understanding bleed, trim and safe zones requires accurate dimension knowledge. Bleed extends 3 to 5 mm beyond the trim edge; safe zone keeps content 3 to 5 mm inside the trim edge. Use our Unit Converter for general measurement conversions, and our Aspect Ratio Calculator to verify proportional dimensions for scaled layouts. Free, no registration required.

Paper Size Converter

A4

❓Frequently Asked Questions

Frequently Asked Questions