Paper Size Converter
Look up paper dimensions for A0–A6, Letter, and Legal sizes in mm and inches.
How to use this tool
- Enter paper size in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your dimensions (mm) and the full breakdown beneath it.
Look up the exact dimensions of any paper size in millimetres and inches.
Formula
ISO A-series: each size is half the area of the previous (A0 = 841 × 1189 mm; A1 = 594 × 841 mm; … A6 = 105 × 148 mm)
Inches = mm ÷ 25.4 (e.g. A4: 210 ÷ 25.4 = 8.27 in ≈ 8.3 in; 297 ÷ 25.4 = 11.69 in ≈ 11.7 in)
North American Letter = 216 × 279 mm (8.5 × 11.0 in); Legal = 216 × 356 mm (8.5 × 14.0 in)
How it works
ISO 216 A-series paper sizes are defined so that each sheet is produced by folding the previous size in half along its longer dimension, maintaining a consistent aspect ratio of 1:√2 (approximately 1:1.414). Dimensions are looked up from the ISO standard table rather than calculated at runtime. A common mistake is printing a document designed for A4 on Letter paper without adjusting margins: A4 is slightly narrower (210 mm vs 216 mm) but taller (297 mm vs 279 mm) than Letter, so content near the bottom of an A4 page will be clipped on a Letter sheet without rescaling.
Worked example
Looking up A4 paper dimensions in mm and inches
- Select paper size A4.
- Look up A4 in the ISO 216 table.
- Dimensions in mm: 210 × 297.
- Convert to inches by dividing each dimension by 25.4: 8.3 × 11.7 in.
Dimensions (mm): 210 x 297 | Dimensions (inches): 8.3 x 11.7
Common mistakes to avoid
- Printing an A4 document on US Letter paper without rescaling -- A4 (210x297 mm) is slightly narrower and taller than Letter (215.9x279.4 mm); content near the bottom margin can be clipped on Letter paper.
- Confusing A4 portrait with A4 landscape dimensions -- A4 landscape is 297x210 mm, not 210x297 mm; orientation matters when specifying print settings.
- Assuming all printers support A3 -- many desktop inkjets max out at A4 or Letter; check printer specs before specifying A3 in a design.
Key terms
- ISO 216
- The international standard defining the A, B, and C series paper sizes, widely used outside North America; the A series is most common for everyday documents.
- A4
- The most widely used ISO paper size globally, measuring 210 × 297 mm (8.3 × 11.7 in); the standard office sheet in Europe, Asia, and most of the world.
- Letter
- The standard North American paper size, measuring 216 × 279 mm (8.5 × 11.0 in); it is slightly wider but shorter than A4.
- Aspect ratio 1:√2
- The defining property of ISO A-series paper: the ratio of short to long side equals 1 to the square root of 2, ensuring the proportions are preserved when folding the sheet in half.
Frequently asked questions
- What size is A4 paper in inches?
- A4 paper measures 210 × 297 mm, which is approximately 8.3 × 11.7 inches.