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Paper Size Converter

Look up any paper size, from A10 to US Legal, and get exact dimensions in millimeters, centimeters and inches, plus area and aspect ratio. Free, instant, no sign-up.

Paper size lookup

Choose a size to see its exact dimensions.

Dimensions

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Width × height: -

Area: -

Aspect ratio: -

Series: -

Scale relationships

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ISO vs US sizes

The A, B and C series follow ISO 216: every size halves the previous one, so A4 is half of A3, and all keep the √2 aspect ratio, which is why scaling never distorts. C sizes are envelopes designed to hold the matching A size.

US sizes like Letter (8.5 × 11 in) and Legal (8.5 × 14 in) follow a different tradition and do not halve neatly.

Reading the dimensions

Dimensions are always width × height in portrait orientation. A4 at 210 × 297 mm is about 8.27 × 11.69 inches. The area readout helps with paper-weight math: multiply m² by gsm to get the sheet weight in grams.

Use the scale relationships to plan folding, booklet imposition or envelope matching.

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Paper Size Converter FAQs

What are the dimensions of A4 in inches?
A4 is 210 × 297 mm, which is 8.27 × 11.69 inches. Select A4 and switch the unit to inches to see it computed live.
Why do A-series sizes halve so neatly?
The √2 aspect ratio means cutting a sheet in half across its long side produces two smaller sheets with the same proportions. That is the whole design idea behind ISO 216.
Which envelope fits A4 paper?
C4. The C series is sized so that C4 holds A4, C5 holds A5, and so on. C5 is the common choice for A4 folded once.
What is the difference between A4 and US Letter?
A4 is 210 × 297 mm (narrower and taller); US Letter is 215.9 × 279.4 mm (wider and shorter). They are not interchangeable for exact-fit printing.
How heavy is a sheet of paper?
Multiply the area in m² by the paper's gsm. An A4 sheet is 0.06237 m², so at 80 gsm it weighs about 5 grams.
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