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Paper Size Calculator

Every common paper size in mm, inches and pixels at the DPI you print at.

DPI

A4 size

210 × 297mm

Scale

Not to scale

All results
In centimeters21 × 29.7cm
In inches8.268 × 11.693in
Pixels at 300 DPI2,480 × 3,508px
Aspect ratio1 : 1.414

A4 is 210 × 297 mm and US Letter is 8.5 × 11 inches (215.9 × 279.4 mm). At 300 DPI that's 2480 × 3508 px and 2550 × 3300 px. Choose a sheet and a resolution to get exact dimensions in every unit, including the pixel size to design at.

How it works

pixels = size (in) × DPI

size (in) = size (mm) ÷ 25.4

Worked example

With A4 in portrait at 300 DPI:

  1. A4 is defined as 210 × 297 mm (ISO 216).
  2. Convert to inches: 210 ÷ 25.4 = 8.26772 in.
  3. Multiply by the DPI and round: 8.26772 × 300 = 2,480.31 ≈ 2480 px wide.

When you need this calculator

Setting up a document or artwork for a specific sheet: a flyer, a poster, a printable PDF or a certificate. Printers need the physical size; design tools want pixels. This gives both, at the resolution you’ll print at, in portrait or landscape.

ISO A and B sizes

The A series starts from A0, one square meter with sides in a 1:√2 ratio, and halves each step. The B series sits between A sizes for posters, books and envelopes: B5 (176 × 250 mm) is between A5 and A4. Dimensions are defined in whole millimeters.

North American sizes

Letter (8.5 × 11 in), Legal (8.5 × 14 in) and Tabloid (11 × 17 in) are defined in inches, so their millimeter values aren’t round numbers. Tabloid (also called Ledger when turned landscape) is roughly the US equivalent of A3.

Pixels and bleed

The pixel sizes here are for the trimmed page. If your design runs to the edge, add bleed first: 3 mm per side for ISO sizes, 0.125 inch per side for US sizes. Then convert with the millimeters to pixels or inches to pixels converter.

Common mistakes

Designing on A4 for a US client, or Letter for a European one. The shapes differ enough that margins and centered layouts shift when printed on the other size.

Treating 96 DPI sizes as print-ready. 794 × 1123 px is A4 at screen resolution. For print, use 300 DPI.

Questions

What size is A4 in pixels?

2480 × 3508 px at 300 DPI, 1240 × 1754 px at 150 DPI, and 794 × 1123 px at 96 DPI.

Is A4 bigger than US Letter?

A4 is 5.9 mm narrower but 17.6 mm taller than Letter. Documents that fit one often need a small scale adjustment to print on the other.

Why is A-series paper that particular shape?

Every A size has sides in the ratio 1:√2 (about 1:1.4142). Cutting one in half gives the next size with exactly the same shape, so A3 folded is A4 and A4 folded is A5.

How big is A0?

841 × 1189 mm, which is an area of about one square meter. Every smaller A size halves the area.

Which countries use Letter instead of A4?

Mainly the United States and Canada, plus Mexico, the Philippines and a few others. Most of the world uses ISO 216 (A4).

Sources

Last reviewed 2026-09-24. How we check values · Report a problem with this page

Further reading