What is the size of A4 paper in mm, cm and inches?

A4 paper is 210 × 297 mm, or 21.0 × 29.7 cm, or 8.27 × 11.69 inches. It is the most widely used international paper size, defined by the ISO 216 standard, and is the standard for business documents, letters and forms in most countries except the United States and Canada.

What is the difference between A4 and US Letter?

A4 (210 × 297 mm) is taller and narrower than US Letter (215.9 × 279.4 mm). Letter is 5.9 mm wider but 17.6 mm shorter than A4. If you print an A4 document on Letter paper without scaling, about 18 mm of content height may be cut off. If you print a Letter document on A4, about 6 mm of width may be lost.

How do I convert paper size to pixels?

Multiply the paper size in inches by the DPI (dots per inch). For A4 at 300 DPI: width = 8.27 × 300 = 2480 pixels, height = 11.69 × 300 = 3508 pixels. This calculator does the conversion automatically for any standard or custom paper size at any DPI from 72 to 9600.

What is the difference between A3 and Tabloid?

A3 (297 × 420 mm) and Tabloid (279.4 × 431.8 mm) are similar but not identical. A3 is wider by 17.6 mm; Tabloid is taller by 11.8 mm. Their aspect ratios differ: A3 follows the ISO 1:√2 ratio; Tabloid follows the US 1:1.545 ratio. They are close enough to substitute with minor margin adjustments, but content may need rescaling.

What is DPI and how does it affect paper size in pixels?

DPI stands for dots per inch — the number of printed dots in one inch of paper. A higher DPI means more detail and a larger pixel file. For web and screen use, 72 or 96 DPI is sufficient. For professional print output, 300 DPI is the standard minimum. For fine art printing or very large formats, 600 DPI may be required.

What are typographic points and picas?

A typographic point is 1/72 of an inch (approximately 0.353 mm). A pica is 12 points, or 1/6 of an inch (approximately 4.233 mm). Both are traditional units used in graphic design and print layout software such as Adobe InDesign and QuarkXPress. A4 in points is 595 × 842 pt — the same as A4 pixel dimensions at 72 DPI.

What are the most common paper sizes worldwide?

The most widely used paper sizes are A4 (used in most countries), US Letter (used in the United States, Canada and parts of Latin America), and A3 (used for larger documents, drawings and posters internationally). B5 is common in Japan for books and notebooks. Legal is used in the US for legal and government documents.

Paper Size Converter — Free Unit Converter | LazyTools

Free Converter · 32 Paper Sizes · All Units

Paper Size Converter

Convert any standard paper size — ISO A series, US Letter, Legal, Tabloid, ANSI, envelopes and photo sizes — to mm, cm, inches, pixels, points and picas. Set DPI, switch portrait/landscape and compare two sizes side by side.

Paper size

Custom dimensions

DPI for pixel output

Compare with

A4 · Portrait · 300 DPI

mm—

cm—

inches—

pixels—

points—

picas—

Size properties

—Area (cm²)

—Aspect ratio

—Diagonal (mm)

—Megapixels

Common size reference

Size	mm (W × H)	in (W × H)

📐 32 paper sizes 6 output units 🖥️ Custom DPI (72–9600) ↕ Portrait & landscape 📊 Visual size comparison ✏ Custom size input 📋 Copy any value

How to Use the Paper Size Converter

All outputs update in real time as you change any setting. Furthermore, you can copy any individual unit value with one click using the copy button next to each row.

Select a paper sizeChoose from the dropdown. Sizes are grouped into ISO A series (A0–A10), ISO B series, ISO C envelopes, US sizes (Letter, Legal, Tabloid), ANSI engineering sizes and common photo print sizes. Furthermore, select Custom to type your own width and height in mm, cm or inches.
Set orientationClick Portrait (tall) or Landscape (wide) in the toolbar. Furthermore, all dimensions swap automatically when you change orientation — no manual input needed. The output title updates to confirm the current orientation.
Choose a DPI for pixel dimensionsSelect a DPI preset — 72 for screen, 300 for professional print — or type a custom value up to 9600. Furthermore, the pixels row updates instantly. The megapixels display shows the total pixel count of the resulting image file.
Read all six output unitsThe right panel shows width × height in millimetres, centimetres, inches, pixels, typographic points and picas simultaneously. Furthermore, click the copy button (⎘) next to any row to copy that value to your clipboard instantly.
Compare two sizes visuallySelect a comparison size from the dropdown to see both paper shapes drawn as scaled outlines. Furthermore, the comparison panel shows the width difference, height difference, area ratio and scale factor between the two sizes.

ISO A-Series Paper Sizes — The International Standard

The ISO A series is the global standard for paper sizes, defined in ISO 216. Furthermore, it is used in virtually every country except the United States and Canada. The system is built around one elegant mathematical property: every size is exactly half the area of the previous size.

A0 is defined as having an area of exactly 1 square metre with an aspect ratio of 1:√2 (approximately 1:1.4142). Furthermore, each successive size — A1, A2, A3, A4 — is obtained by folding the previous size in half across its longest edge. This means folding A3 in half gives A4. Folding A4 gives A5. Additionally, the aspect ratio is always preserved, so content scales cleanly between sizes without distortion.

Size	Width (mm)	Height (mm)	Inches (W × H)	Common use
A0	841	1189	33.11 × 46.81	Technical drawings, large posters
A1	594	841	23.39 × 33.11	Architectural plans, posters
A2	420	594	16.54 × 23.39	Presentation boards, large prints
A3	297	420	11.69 × 16.54	Spreadsheets, drawings, small posters
A4	210	297	8.27 × 11.69	Letters, forms, standard documents
A5	148	210	5.83 × 8.27	Notepads, flyers, personal planners
A6	105	148	4.13 × 5.83	Postcards, index cards, small booklets

The 1:√2 aspect ratio of the ISO A series is unique in paper standards. Furthermore, it is the only ratio where folding a rectangle in half produces two smaller rectangles with the same proportions. This property makes A-series paper the most versatile standard for reproduction — scaling between sizes always works perfectly.

US Paper Sizes — Letter, Legal and Tabloid

The United States uses a different paper size system from the rest of the world. Furthermore, US sizes are defined in inches rather than millimetres, and they do not follow the 1:√2 aspect ratio of ISO sizes. The three most common are Letter, Legal and Tabloid.

Letter (8.5 × 11 inches, 215.9 × 279.4 mm) is the US equivalent of A4. Furthermore, it is the default paper size for most printers, word processors and documents in the United States and Canada. Legal (8.5 × 14 inches) is the same width as Letter but 3 inches taller. Additionally, Tabloid (11 × 17 inches) is used for newspapers, newsletters and landscape-format spreadsheets.

Letter (8.5 × 11 in)

215.9 × 279.4 mm. The standard US office document size. Furthermore, it is 5.9 mm wider and 17.6 mm shorter than A4. This small difference causes significant margin problems when sharing documents internationally. Always check page setup before printing a US Letter document on A4 paper.

Legal (8.5 × 14 in)

215.9 × 355.6 mm. The same width as Letter with an additional 3 inches of height. Furthermore, Legal is used for government and legal filings, contracts and deeds that require more content on a single page. It has no direct ISO equivalent.

Tabloid (11 × 17 in)

279.4 × 431.8 mm. Closest to A3 but not identical. Furthermore, Tabloid is used for newspapers, brochures and spreadsheets in landscape orientation. It is referred to as Ledger when used in landscape format. The aspect ratio (1:1.545) differs from A3 (1:1.414).

Executive (7.25 × 10.5 in)

184.1 × 266.7 mm. Slightly smaller than Letter, traditionally used for executive correspondence and private stationery. Furthermore, Executive is between A5 and A4 in both dimensions and has no direct international equivalent.

ISO B and C Series — Books, Envelopes and Larger Formats

The ISO B series fills the gaps between A sizes. Furthermore, each B size has dimensions that are the geometric mean of the corresponding A size and the next larger A size. B5 (176 × 250 mm) sits between A4 and A5 and is widely used for books, particularly in Japan and other Asian countries.

The ISO C series is specifically designed for envelopes. Furthermore, a C4 envelope (229 × 324 mm) fits an A4 sheet unfolded. A C5 envelope fits an A4 sheet folded in half. A C6 envelope fits an A5 sheet or an A4 sheet folded twice. Additionally, the DL envelope (110 × 220 mm) fits an A4 sheet folded into thirds — this is the most common business envelope format worldwide.

The ISO envelope system is designed so that A-size paper always fits perfectly into the corresponding C envelope without cutting or folding to a non-standard size. Furthermore, an A4 letter placed in a C4 envelope fits unfolded. Folded once, it fits a C5. This makes the C series the perfect complement to the A series for business correspondence.

DPI, Pixels and Digital Paper Dimensions

DPI (dots per inch) defines the resolution of a printed document. Furthermore, it connects the physical size of paper to the pixel dimensions of a digital file. Multiply the paper width in inches by the DPI to get the pixel width. A4 at 300 DPI: 8.27 × 300 = 2480 pixels wide.

Different workflows require different DPI values. Furthermore, screen-only documents can use 72 or 96 DPI — the traditional screen resolution. Draft prints work well at 150 DPI. Professional print production requires 300 DPI as the minimum. Fine art giclée printing and very large-format output often uses 600 DPI or higher. Additionally, setting DPI too high wastes file space without visible quality improvement when the final output is screen-only.

DPI	A4 pixels (W × H)	Use case	File size (JPEG approx.)
72	595 × 842	Screen display, web	~200 KB
96	794 × 1123	Standard screen, Office exports	~350 KB
150	1240 × 1754	Draft print, general review	~850 KB
300	2480 × 3508	Professional print (minimum)	~3.5 MB
600	4961 × 7016	High-quality print, giclée	~14 MB

Typographic Points and Picas

Points and picas are traditional typographic units used in graphic design and print layout. Furthermore, they remain the standard measurement units in professional design software including Adobe InDesign, Illustrator and QuarkXPress. Understanding them is essential for print design work.

One typographic point is exactly 1/72 of an inch, or approximately 0.353 mm. Furthermore, 12 points make one pica. One pica is therefore 1/6 of an inch, or approximately 4.233 mm. An A4 page in points is 595 × 842 pt — the same as A4 pixel dimensions at 72 DPI, which is not a coincidence. PDF documents use points as their native unit internally.

Points in practice

Body text in print documents is typically set at 10–12 pt. Headings at 16–24 pt. Margins, column gutters and spacing are also specified in points in InDesign and similar tools. Furthermore, font sizes are always specified in points, making this unit the primary typographic measurement.

Picas in practice

Picas are used for column widths, text frame dimensions and grid layouts. Furthermore, a pica is roughly the width of a capital M in 12 pt text. The em unit in CSS (used on screen) derives from the same concept. A standard column width in a newspaper is typically 12–14 picas.

A4 vs US Letter — The Global Paper Size Divide

A4 and US Letter are the world's two dominant paper sizes, and the confusion between them causes practical problems daily. Furthermore, they are visually similar — close enough to fit in the same paper tray — but their proportions are meaningfully different.

A4 is taller and narrower: 210 × 297 mm (8.27 × 11.69 in). US Letter is shorter and wider: 215.9 × 279.4 mm (8.5 × 11 in). Furthermore, Letter is 5.9 mm wider but 17.6 mm shorter. When a European prints a Letter-format document on A4 paper, the bottom 17.6 mm may be cut off or forced to a second page. Additionally, when an American prints an A4 document on Letter, the right edge may be trimmed or margins compressed.

The safest approach when sharing documents internationally is to set larger margins — at least 25 mm on all sides for A4, or 1.25 inches on all sides for Letter. Furthermore, this buffer ensures the document fits on either paper size without content loss. PDF files exported to specific paper sizes always embed the page dimensions, so the recipient's printer should respect the intended size.

Choosing the Right Paper Size for Your Project

Paper size selection affects readability, production cost, mailing cost and environmental footprint. Furthermore, using the wrong size means either wasted margin space or content being forced onto additional pages.

Office documents

Use A4 internationally or Letter in the US. Furthermore, most word processors and PDF readers default to these sizes. If the document will be shared internationally, use A4 with generous margins so it prints correctly on Letter without content loss.

Posters and large prints

A3 is the minimum for a readable wall poster. A2 and A1 are better for display at normal viewing distances. Furthermore, if you need a specific pixel count, use this converter to find the pixel dimensions at your required DPI before starting the design.

Books and publications

B5 (176 × 250 mm) is the standard trade book format in many countries. A5 is common for pocket-sized publications, workbooks and manuals. Furthermore, business card standard is 85.6 × 54 mm (ISO 7810 ID-1), the same size as a credit card.

Frequently Asked Questions

A4 is 210 × 297 mm, or 21.0 × 29.7 cm, or 8.27 × 11.69 inches. Furthermore, at 300 DPI it is 2480 × 3508 pixels. It is the most widely used paper size in the world, the standard for business documents in most countries and the default size in word processors and printers outside North America.

A4 (210 × 297 mm) is taller and narrower than US Letter (215.9 × 279.4 mm). Furthermore, Letter is 5.9 mm wider but 17.6 mm shorter than A4. Printing an A4 document on Letter paper may cut off the bottom 18 mm of content. Printing a Letter document on A4 may cut off about 6 mm of width.

Multiply the paper width and height in inches by your target DPI. A4 at 300 DPI: 8.27 × 300 = 2480 pixels wide, 11.69 × 300 = 3508 pixels tall. Furthermore, this converter calculates pixel dimensions automatically for any standard or custom paper size at any DPI from 1 to 9600.

A4 at 300 DPI is 2480 × 3508 pixels in portrait orientation. Furthermore, at 72 DPI it is 595 × 842 pixels. At 96 DPI it is 794 × 1123 pixels. At 150 DPI it is 1240 × 1754 pixels. The 72 DPI value is also the page size in PDF points, since 1 point = 1/72 inch.

The ISO A series defines paper sizes using an aspect ratio of 1:√2 and an A0 area of exactly 1 square metre. Furthermore, each successive size (A1, A2, A3…) is exactly half the previous size. Folding A4 in half gives A5. This means the aspect ratio is always preserved when scaling between A sizes.

A3 (297 × 420 mm) and Tabloid (279.4 × 431.8 mm) are similar but not identical. A3 is 17.6 mm wider; Tabloid is 11.8 mm taller. Furthermore, their aspect ratios differ: A3 uses the ISO 1:√2 ratio; Tabloid uses 1:1.545. Content may need minor rescaling to move between the two formats.

The professional print standard is 300 DPI for most documents and photographs. Furthermore, draft prints and proofs can use 150 DPI. Screen-only documents need only 72 or 96 DPI. High-quality giclée art prints and very large formats may require 600 DPI. Higher DPI creates larger file sizes with no visible quality benefit at normal viewing distances.

One point is 1/72 of an inch (0.353 mm). Furthermore, 12 points make one pica (4.233 mm = 1/6 inch). Both are used in professional design software like InDesign. An A4 page is 595 × 842 pt — the same as its 72 DPI pixel dimensions — because 1 point = 1/72 inch = 1 screen pixel at 72 DPI.

A C4 envelope (229 × 324 mm) holds an A4 sheet unfolded. A C5 envelope (162 × 229 mm) holds an A4 sheet folded once (in half). Furthermore, a DL envelope (110 × 220 mm) holds an A4 sheet folded into thirds — this is the most common business envelope used worldwide. The C series is designed specifically to complement the A series.

References and Sources

Paper size dimensions and standards used in this tool draw from the following authoritative sources. Furthermore, all dimensions are exact as defined in the relevant ISO and ANSI standards.

ISO 216:2007 — Writing paper and certain classes of printed matter

International Organization for Standardization (ISO) · ISO 216:2007 · Writing Paper Standards

The definitive international standard defining the A and B series paper sizes used worldwide. Specifies A0 as 841 × 1189 mm with an area of exactly 1 m², the 1:√2 aspect ratio maintained across all sizes, and the trimming tolerances (±1.5 mm for sizes up to 150 mm, ±2 mm for sizes between 150 mm and 600 mm, ±3 mm for larger sizes). All ISO A and B series dimensions in this calculator are taken directly from ISO 216:2007.

📋 Primary standard

ANSI/ASME Y14.1 — Decimal Inch Drawing Sheet Size and Format

American National Standards Institute (ANSI) / American Society of Mechanical Engineers (ASME) · Engineering Drawing Standards

Defines the ANSI engineering drawing sheet sizes (A through E) used in US technical and engineering documentation. ANSI A (8.5 × 11 in) through ANSI E (34 × 44 in) form the basis of the ANSI engineering size series included in this converter. Also defines title block and border requirements for engineering drawings on each sheet size.

📋 Engineering standard

ISO 269 — Correspondence envelopes: designation, sizes and tolerances

International Organization for Standardization (ISO) · ISO 269 · Envelope Standards

Defines the C series ISO envelope sizes (C3, C4, C5, C6, DL and others) that are specifically designed to hold A-series paper in unfolded, once-folded or twice-folded configurations. Specifies that C4 (229 × 324 mm) holds unfolded A4, C5 (162 × 229 mm) holds A4 folded once, and DL (110 × 220 mm) holds A4 folded in thirds. All envelope dimensions in this converter are drawn from ISO 269.

📋 Envelope standard

DPI vs PPI: What's the Difference?

Adobe Creative Cloud · Design Hub · Print and digital resolution guidance

Adobe's authoritative guide on DPI (dots per inch for print) and PPI (pixels per inch for screens), covering the standard DPI values for different print outputs (72 for screen, 150 for draft, 300 for professional print, 600+ for fine art) and how to calculate pixel dimensions from physical paper size and target DPI. Referenced for the DPI presets and the DPI-to-pixel calculation methodology used in this converter.

📖 DPI methodology

Paper Size — Wikipedia

Wikipedia · The Free Encyclopedia · Citing ISO 216, ANSI, DIN and national standards

A comprehensive reference covering the history of international and national paper size standards, the mathematical derivation of the 1:√2 ratio, a full comparison of A, B and C series dimensions, US ANSI sizes, Japanese JIS B series, and the typographic point and pica system. Referenced for the A4 vs Letter comparison dimensions, the ISO B series intermediate sizes, and the historical context of why different regions adopted different paper size standards.

📚 Background reference

Paper Sizes — Prepressure

Prepressure.com · Pre-press and printing technical reference · Regularly updated

A detailed practitioner reference for paper sizes used in commercial printing, covering ISO, North American, Japanese and special-purpose sizes with dimensions in all major units, common use cases per size, and guidance on bleed, trim and safe zone specifications. Referenced for the practical applications of each paper size listed in this converter's comparison table, and for the photo print sizes (4R, 5R, 6R, 8R, 10R) which follow a Japanese-origin naming convention.

📖 Practitioner reference

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