Converter

Paper Size Converter

Compare paper sizes including Letter, A4, Legal, Tabloid, and ISO standards. Dimensions in millimeters and inches.

Quick Answer

A4 is 210 × 297mm (8.27 × 11.69"). US Letter is 216 × 279mm (8.5 × 11"). A4 is slightly narrower and taller than Letter.

Filter by Category

NameSize (mm)Size (inches)Category
A0841 × 118933.1 × 46.8ISO A
A1594 × 84123.4 × 33.1ISO A
A2420 × 59416.5 × 23.4ISO A
A3297 × 42011.7 × 16.5ISO A
A4210 × 2978.27 × 11.69ISO A
A5148 �� 2105.83 × 8.27ISO A
A6105 × 1484.13 × 5.83ISO A
Letter216 × 2798.5 × 11North American
Legal216 × 3568.5 × 14North American
Tabloid279 × 43211 × 17North American
Executive184 × 2677.25 × 10.5North American
B4250 × 3539.84 × 13.9ISO B
B5176 × 2506.93 �� 9.84ISO B
C4 Envelope229 × 3249.02 × 12.76ISO C
C5 Envelope162 × 2296.38 × 9.02ISO C
DL Envelope110 × 2204.33 × 8.66ISO C

About Paper Sizes

Paper sizes around the world fall into two main families: the ISO 216 standard (A, B, and C series) used by most countries, and the North American sizes (Letter, Legal, Tabloid) used primarily in the US and Canada. Understanding paper sizes is important for printing, design, international correspondence, and document preparation.

The ISO A Series

The ISO A series is based on an elegant mathematical principle. A0 has an area of exactly one square meter. Each subsequent size (A1, A2, A3, etc.) is exactly half the area of the previous size, achieved by cutting the longer dimension in half. All sizes maintain the same aspect ratio of 1:sqrt(2), approximately 1:1.414. This means you can scale documents between A sizes without cropping or distortion.

A4 vs US Letter

A4 (210 x 297mm) and US Letter (216 x 279mm) are the two most commonly used paper sizes worldwide. A4 is 6mm narrower but 18mm taller than Letter. This difference causes formatting issues when sharing documents internationally. PDF documents should specify the target paper size, and printers should be set to the correct size to avoid unexpected cropping or scaling.

Choosing the Right Paper Size

For most everyday printing, use your country's standard: A4 for most of the world, Letter for the US and Canada. Legal size is common for contracts and legal documents in the US. Tabloid (11x17) is used for small posters and newspaper-style layouts. A3 is popular for architectural plans and large format printing. Envelopes in the C series are designed to hold the corresponding A series paper.

Frequently Asked Questions

What is the difference between A4 and Letter?
A4 is 210 × 297mm (8.27 × 11.69 inches). US Letter is 216 × 279mm (8.5 × 11 inches). A4 is narrower and taller. This difference can cause formatting issues when sharing documents between countries.
Which paper size is used in the US?
The US primarily uses Letter (8.5 × 11 inches) for everyday documents, Legal (8.5 × 14 inches) for legal documents, and Tabloid (11 × 17 inches) for larger format printing.
What is the largest standard paper size?
In the ISO series, A0 is the largest at 841 × 1189mm (about 33 × 47 inches) with an area of one square meter. Larger sizes exist for architectural and engineering drawings but are less standardized.
Why does A series paper have that specific aspect ratio?
The A series uses a 1:√2 ratio (approximately 1:1.414). This ensures that when you cut a sheet in half along its longer dimension, the resulting halves maintain the same proportions. This makes scaling between sizes seamless.
What envelope fits A4 paper?
A C4 envelope (229 × 324mm) fits A4 paper flat without folding. A C5 envelope fits A4 folded once. A DL envelope (110 × 220mm) fits A4 folded into thirds, which is the standard business letter format in most countries.

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