A4 paper Size in Inches & cm

A4 paper is 210 x 297 mm, or 8.27 x 11.69 inches. It is the standard document size almost everywhere except the United States and Canada, where US Letter is used instead. A single 80 gsm sheet weighs about 5 grams.

This guide covers the exact A4 dimensions in every common unit, how it differs from US Letter and the sizes above and below it, and how a sheet compares to a tablet, a laptop, and a clipboard.

Quick Answer: How Big Is A4 Paper?

A4 measures 210 x 297 mm (21.0 x 29.7 cm, 8.27 x 11.69 in). Its area is 1/16 of a square metre (0.0625 m2). It is exactly half of A3 and twice A5, and the sides are in the ratio 1 : root 2 (about 1 : 1.414).

A4 Paper Dimensions at a Glance

• Size: 210 x 297 mm / 21.0 x 29.7 cm / 8.27 x 11.69 in
• Relationship: half of A3 (297 x 420 mm), double A5 (148 x 210 mm)
• Pixels at 300 DPI (print): 2480 x 3508 px
• Pixels at 96 DPI (screen): 794 x 1123 px
• Common weights: 80 gsm (5.0 g), 90 gsm (5.6 g), 120 gsm (7.5 g), 160 gsm card (10.0 g), 250 gsm card (15.6 g)

What Does A4 Paper Look Like in Size?

A4 is the reference object most people picture for “a sheet of paper.” It is a little larger than a 10-inch tablet, close to the deck size of a 13-inch laptop, and it slides into a standard folder, envelope (C4 unfolded, DL folded in three), and clipboard without trimming. Held upright it runs from a desktop to about elbow height.

6 Everyday Comparisons for A4 Paper

1. A US Letter sheet (215.9 x 279.4 mm) is 5.9 mm wider and 17.6 mm shorter than A4.
2. An A3 sheet (297 x 420 mm) is exactly two A4 sheets side by side.
3. An A5 sheet (148 x 210 mm) is exactly half an A4.
4. A 13-inch MacBook Air (304 x 212 mm closed) is about 7 mm wider and 5 mm shorter than A4… roughly the same footprint.
5. A 10-inch iPad (about 250 x 175 mm) is smaller than A4 in both directions.
6. A vinyl record (300 mm) matches A4’s width and is much shorter.

A4 Paper Size in Different Units

A4 vs US Letter

A4 is narrower and taller, and its root-2 proportion is more elongated. A document laid out for Letter and printed on A4 gains side margin and loses bottom margin, and vice versa, which is why PDFs sometimes print with a shifted layout across the two regions.

Why the A Series Works the Way It Does

A0 is one square metre of paper with its sides in the ratio 1 : root 2. Cutting any A size in half across the long side gives the next size down with the same proportions, so A4 folded in half is A5, and two A4 sheets make A3. Because the ratio never changes, you can enlarge A4 artwork to A3 at exactly 141% or reduce it to A5 at 71% with nothing cropped. A4 is the fourth cut down from A0.

Common Mistakes When Comparing A4 Paper

1. Assuming A4 and US Letter are interchangeable. They differ by about 6 mm in width and 18 mm in height, enough to shift a full-bleed layout.
2. Thinking A4 is exactly 30 cm tall. It is 29.7 cm.
3. Using screen pixels as the size. A4 only has a fixed pixel count once you set the DPI (300 for print).
4. Confusing “A4” with a paper weight. A4 is a size; 80 gsm is the weight of typical copier paper at any size.
5. Halving the length instead of the area. A4 is half the area of A3, not half its length.

Frequently Asked Questions

How big is A4 paper in cm?

21.0 x 29.7 cm.

How big is A4 paper in inches?

8.27 x 11.69 inches.

Is A4 the same as US Letter?

No. A4 is 210 x 297 mm; US Letter is 215.9 x 279.4 mm, so it is wider and shorter.

What is A4 in pixels?

2480 x 3508 px at 300 DPI; 794 x 1123 px at 96 DPI.

Is A4 half of A3?

Yes. Two A4 sheets side by side make one A3.

How much does a sheet of A4 weigh?

About 5 g at 80 gsm.

How do I scale A4 to A3?

Enlarge to 141%; the proportions match exactly.

Final Takeaway

A4 paper is 210 x 297 mm (8.27 x 11.69 in) and weighs about 5 grams per 80 gsm sheet. It is half of A3, double A5, and keeps the same 1 : root 2 shape at every step, and it is narrower and taller than US Letter, so layouts do not swap between the two regions without margin changes.