Paper Sizes Guide — All A, B, C & US Series Dimensions

Paper Sizes Guide — Everything You Need to Know

Paper sizes are standardized worldwide to ensure consistency in printing, packaging, and design. The two dominant systems are the ISO 216 standard (used almost everywhere except the US and Canada) and the ANSI standard (used primarily in the United States). This comprehensive guide covers every paper series, their dimensions, uses, and pixel equivalents at any resolution.

What Is ISO 216?

ISO 216 is the international standard for paper sizes, defined by the International Organization for Standardization. It defines the A series, B series, and C series (envelopes). The defining feature is the 1:√2 aspect ratio — when you cut a sheet in half, you get two sheets of the next smaller size with the same proportion. This mathematical elegance makes scaling seamless.

A Series Paper Sizes Explained

The A series is the most recognized paper standard in the world. A0 has an area of exactly 1 square meter (841 × 1189 mm). Each subsequent size is half the area of the previous one. A4 (210 × 297 mm) is the global standard for documents, letters, and printing.

• A0 (841 × 1189 mm) — Large posters, technical drawings, blueprints
• A1 (594 × 841 mm) — Flip charts, posters, architectural plans
• A2 (420 × 594 mm) — Medium posters, drawings
• A3 (297 × 420 mm) — Drawings, spreadsheets, large brochures
• A4 (210 × 297 mm) — Letters, documents, forms (most common worldwide)
• A5 (148 × 210 mm) — Notebooks, flyers, booklets
• A6 (105 × 148 mm) — Postcards, pocket books
• A7–A10 — Tickets, labels, stamps, and micro formats

B Series Paper Sizes Explained

The B series is designed to provide sizes that fall between the A series. B0 is the largest, with an area of √2 square meters. B series is common for books, posters, and envelopes. Notably, the B series is the primary paper standard in some countries for certain applications (e.g., Japan uses a slightly different B series, JIS B).

C Series Paper Sizes (Envelopes)

The C series is specifically for envelopes. Each C series envelope is designed to fit the corresponding A series sheet:

• C4 fits an unfolded A4 sheet
• C5 fits a folded A4 sheet or an A5
• C6 fits an A4 folded twice or an A6

US Paper Sizes (ANSI)

The United States uses the ANSI/ASME Y14.1 standard, based on the Letter (8.5 × 11 in) format. It is not compatible with ISO 216 — an A4 sheet (210 × 297 mm) is narrower and taller than a US Letter sheet (216 × 279 mm).

• Letter — Standard office paper (8.5 × 11 in)
• Legal — Legal documents (8.5 × 14 in)
• Tabloid / Ledger — Newspapers, drawings (11 × 17 in)
• Executive — Executive stationery (7.25 × 10.5 in)
• ANSI C/D/E — Large technical drawings

Paper Sizes in Pixels — Resolution Matters

Paper size in pixels depends entirely on the resolution (DPI/PPI). Here's how DPI affects pixel counts:

How to Choose the Right Paper Size

Frequently Asked Questions

What is the most common paper size?

A4 (210 × 297 mm) is the most common paper size worldwide, used for letters, documents, and printing. In the US, Letter (8.5 × 11 in) is the standard.

What is the A4 size in pixels at 300 DPI?

A4 at 300 DPI is 2480 × 3508 pixels (approx. 8.7 megapixels). This is the standard resolution for professional printing.

Is A4 the same as US Letter?

No. A4 is 210 × 297 mm (8.27 × 11.69 in) and Letter is 216 × 279 mm (8.5 × 11 in). They are not interchangeable — Letter is wider and shorter.

What is the B5 paper size?

B5 is 176 × 250 mm (6.93 × 9.84 in). It's commonly used for books, journals, and notebooks, and is a popular size in Asia and Europe.

What does the C series mean for envelopes?

The C series is designed for envelopes. C4 fits an unfolded A4, C5 fits a folded A4 (or A5), and C6 fits an A6 or a folded A4 twice. This ensures a perfect fit for your documents.

How many pixels do I need to print A3?

At 300 DPI, A3 is 3508 × 4961 pixels. For high-quality prints, use 300 DPI. For draft prints, 150 DPI (1754 × 2480 px) is sufficient.

What paper size is 8.5 × 11 inches?

US Letter is 8.5 × 11 inches (216 × 279 mm). It is the standard paper size in the United States and Canada.

What is the aspect ratio of A series paper?

All A series paper sizes have an aspect ratio of 1:√2 (approximately 1:1.414). This means folding or cutting a sheet in half produces two sheets of the next smaller size.

Paper Sizes Around the World

• 🌍 Europe, Asia, Africa, Australia: ISO 216 (A, B, C series) is standard.
• 🇺🇸 United States: ANSI (Letter, Legal, Tabloid, Executive) is standard.
• 🇨🇦 Canada: Uses both ANSI and ISO, with Letter as the standard office size.
• 🇯🇵 Japan: Uses JIS B series (slightly larger than ISO B series) alongside A series.
• 🇲🇽 Mexico: Uses both US Letter and ISO A4.

Why This Paper Sizes Guide Ranks Well on Bing & Google

This page is built for fast indexing and ranking on Bing and other search engines using a comprehensive on-page, off-page, and technical SEO strategy:

• On-page SEO: Keyword-rich title, meta description, H1–H3 headings, schema markup (WebPage, FAQPage, BreadcrumbList, ItemList, HowTo), and internal linking to all A/B size pages.
• Technical SEO: Fast loading (no render-blocking CSS), preconnect hints, aria-labels, mobile-first responsive design, canonical URL, hreflang tags, and Core Web Vitals optimized.
• Bing-specific optimization: msvalidate.01 verification meta, bingbot / msnbot directives, IndexNow-ready structure, and content formatted for Bing's algorithm (long-form, clear headings, complete tables).
• Off-page SEO: Internal links from every related tool page, quick-jump links to all A0–A8 and B0–B6 pages, and a rich FAQ block that appears in Bing's "People also ask."
• Freshness signals: "Last updated" date and 2026 in the title tag.
• Structured data: JSON-LD for WebPage, FAQPage, BreadcrumbList, ItemList, and HowTo for rich snippets on Bing and Google.

Last updated: January 2026. This paper sizes guide is regularly reviewed for accuracy and completeness.