Paper Sizes: A4, Letter and More
These paper sizes cover A4 (210 × 297 mm, 8.27 × 11.69 in), the whole A, B and C series, US Letter, Legal and card formats in mm, cm, inches, points and pixels at any resolution.
Example: Format: A4 · Unit: Millimetres (mm) → Size: A4: 210 × 297 mm. Source: ISO 216:2007 – Writing paper and certain classes of printed matter: Trimmed sizes, A and B series. Updated: .
How it is calculated
A4 measures 210 × 297 mm, which is 21 × 29.7 cm or 8.27 × 11.69 inches. At 300 dpi A4 is 2480 × 3508 pixels, at 72 dpi it is 595 × 842 points.
How the series is built
All A-series sizes share the aspect ratio 1 : √2 (about 1 : 1.414). The base size A0 has an area of 1 m² (841 × 1189 mm). Every following size is made by halving the long side, rounded down to whole millimetres: two A4 sheets make an A3. The B series (ISO 216) starts with a width of 1000 mm for posters and folders, and the C series (ISO 269) is for envelopes: a C4 envelope holds an A4 sheet flat, C5 an A5 or A4 folded once, and DL (110 × 220 mm) an A4 folded twice.
Good to know
- The US and Canada use Letter (8.5 × 11 in) and Legal (8.5 × 14 in); they do not fit A4 printers exactly, and vice versa.
- Japan's B series differs: JIS B5 is 182 × 257 mm, ISO B5 is 176 × 250 mm. Both are in the table.
- Pixel sizes depend on resolution: 300 dpi is common for print, 72 to 96 dpi for screens.
- Card formats: bank and ID cards are 85.60 × 53.98 mm (ISO/IEC 7810 ID-1), business cards in Europe are usually 85 × 55 mm.
Frequently asked questions
What size is A4 in inches?
8.27 × 11.69 inches, which is 210 × 297 mm or 21 × 29.7 cm.
How many pixels is A4?
At 300 dpi it is 2480 × 3508 pixels, at 150 dpi 1240 × 1754, at 72 dpi 595 × 842 and at 96 dpi 794 × 1123 pixels.
What is half of A4?
A5, at 148 × 210 mm. Conversely, two A4 sheets make an A3 (297 × 420 mm).
What is the difference between A4 and US Letter?
Letter is 215.9 × 279.4 mm, a little wider and shorter than A4. The aspect ratio differs, so margins shift when printing on the other format.
Sources and legal basis
- ISO 216:2007 – Writing paper and certain classes of printed matter: Trimmed sizes, A and B series
- Wikipedia – Paper size (A-, B-, C-Reihe, JIS B, ANSI-Formate)
- Wikipedia – ISO 216 (aspect ratio 1 : √2, rounding of the dimensions)
- ISO/IEC 7810 – ID-1 (85,60 × 53,98 mm)
As of: · Editorial policy
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