What Size is A5 Paper? Dimensions in mm, cm, Inches

If you’ve ever folded a sheet of A4 paper in half and wondered what size you just made, you were holding an A5. That simple geometric relationship—each A size is exactly half the previous one—is at the heart of an international standard that governs paper across most of the world. This article gives you the exact dimensions of A5 in millimeters, centimeters, and inches, shows how it compares to A4, A6, and the US Letter format, and explains why the proportions stay consistent no matter which size you pick.

A5 Dimensions: 148 × 210 mm · A5 in Inches: 5.8 × 8.3 in · Half of A4: Yes · ISO Standard: A-series · Common Uses: Booklets, notepads

The table below consolidates the essential A5 specifications for quick reference.

What size is an A5?

The A5 paper size is defined as 148 millimeters wide by 210 millimeters tall, based on the ISO 216 international standard. This size falls between the more familiar A4 and the smaller A6 in the A-series hierarchy. When converted to inches, A5 measures approximately 5.83 by 8.27 inches, which is commonly rounded to 5.8 by 8.3 inches for everyday use (Dimensions.com paper specs).

A5 in mm and cm

Because the metric system aligns naturally with the ISO standard, A5 dimensions are straightforward: 148 × 210 mm translates directly to 14.8 × 21.0 cm. All A-series sizes share the same aspect ratio of 1:√2 (approximately 1:1.414), which means that when you cut a sheet parallel to its shorter side, the resulting proportions remain identical (Wikipedia ISO paper standards).

A5 in inches

The imperial equivalent of A5 is often cited as 5.8 × 8.3 inches, though the more precise figure is 5.83 × 8.27 inches. This slight difference matters for precision work like print production, where exact measurements ensure proper alignment on press. The rounded figures are sufficient for general office use and most desktop publishing contexts (Formax Printing paper guide).

A5 in pixels

Pixel dimensions depend entirely on the output resolution. At 72 DPI (screen resolution), an A5 image measures roughly 420 × 595 pixels. At 150 DPI (draft print quality), it becomes approximately 874 × 1,232 pixels. For print-ready files at 300 DPI—the standard for commercial printing—an A5 image requires 1,748 × 2,480 pixels. At 600 DPI (high-quality offset), the dimensions jump to 3,496 × 4,960 pixels.

“The size of A5 paper is half of A4, i.e. 148 mm × 210 mm (5.8 in × 8.3 in).”

— Wikipedia, International Standard Paper Sizes

Is A5 size half of A4?

Yes, A5 is precisely half the size of A4 paper. When you cut an A4 sheet parallel to its shorter edge, you produce two A5 sheets. This is not approximate—it is a mathematical relationship baked into the ISO 216 standard. A4 measures 210 × 297 mm, and halving the 210 mm width gives you 105 mm, while halving the 297 mm height gives you 148.5 mm, which rounds to the standard 148 mm (Dimensions.com paper specs).

Exact dimensions comparison

The comparison table below shows how A4, A5, and A6 relate mathematically within the A-series.

The implication for designers is that scaling between A-series sizes follows a predictable ratio—A5 at 141% becomes A4, and A4 at 71% becomes A5.

Folding A4 to A5

In practice, folding an A4 sheet does not produce a perfect A5—the fold creates a slight ridge and the sheet thickens at the crease. However, the printed area of a folded A4 pamphlet often matches the A5 trim size, which is why this relationship is useful for designing brochures that will be machine-folded (Swift Publisher size guide).

Which is bigger, A5 or A6?

A5 is larger than A6. A5 measures 148 × 210 mm, while A6 is 105 × 148 mm. Cutting an A5 sheet in half along its shorter side produces two A6 sheets, following the same halving logic that connects the entire A-series (Papersizes.org A-series reference).

A5 vs A6 dimensions

The A6 format is roughly the size of a standard postcard. In imperial units, A6 is approximately 4.13 × 5.83 inches, which is close to the common US postcard size of 4 × 6 inches (Avery paper comparison guide). A5 is about 2.1 times larger in area than A6, making it better suited for booklet covers, small notepads, and flyers.

“A6 is half the size of A5 paper. A5 is 148 mm × 210 mm; A6 is 105 mm × 148 mm.”

— Avery, Compare A4, A5, A6 Paper to US Letter

A6 from halving A5

Because each A-series size is mathematically derived from the next larger one, A6 is created by halving A5 along its shorter edge. The 148 mm width becomes 74 mm on each half (rounded to the standard 74 mm), and the 210 mm height becomes 105 mm. This consistent halving mechanism is what makes the A-series so practical for printing and binding operations (Wikipedia ISO paper standards).

What size is A4?

A4 is the most widely used paper format in the world, measuring exactly 210 × 297 mm or 8.27 × 11.69 inches. It is the standard office printing size outside North America, appearing in virtually every copy center, printer default setting, and office supply aisle in Europe, Asia, and most of Latin America (Papersizes.org A-series reference).

A4 in mm, cm, inches

The table below breaks down A4 dimensions across all three common measurement systems.

The pattern shows that all A-series dimensions scale predictably using the √2 aspect ratio, which simplifies layout scaling across formats.

A4 vs US Letter

US Letter, the standard format in North America, measures 216 × 279 mm (8.5 × 11 inches). This means US Letter is slightly wider but shorter than A4. The difference is small—about 6 mm narrower and 18 mm shorter—but it is enough to cause document formatting problems when switching between regions. A4’s narrower profile and longer length come from its √2 aspect ratio, which US Letter does not share (Wikipedia ISO paper standards).

Professionals exchanging documents internationally should verify paper settings before printing to avoid waste and rework.

A1, A2, A3, A4 paper sizes

The A-series extends well beyond A4 and A5, reaching sizes used for architectural drawings, posters, and large-format printing. The series starts at A0, which has an area of exactly 1 square meter (841 × 1,189 mm), and each subsequent size halves the previous one.

Full A-series progression

The table below shows all A-series sizes from A0 to A6 with their dimensions and typical applications.

The catch for users selecting paper sizes is that each halving step also halves the area, so A3 is not simply a smaller A4—it contains exactly four times less surface area.

Common uses by size

• A0–A1: Engineering blueprints, GIS maps, large event posters
• A2–A3: Architectural presentations, art prints, newspaper prototypes
• A4: Business correspondence, reports, standard printing
• A5: Pocket notebooks, promotional flyers, program booklets
• A6: Postcards, thank-you cards, appointment reminders

Summary

A5 paper is 148 × 210 mm (5.83 × 8.27 in), exactly half the area of A4, and a practical middle ground between full-size office paper and small postcard formats. The ISO 216 standard that defines these dimensions ensures consistency across every country that uses the A-series, which is most of the world outside North America. For anyone designing printed materials—whether for international distribution or local markets—the A5 size offers a compact format that fits standard envelope inserts and copiers while providing enough space for readable content. Printers in North America can accommodate A5, though US Letter remains the default; switching to A5 in your printer settings unlocks a format that many international partners and customers expect as the norm.

Businesses targeting global markets should consider adopting A5 as a standard format for brochures and product sheets, reducing the need for region-specific reprints.

Related reading: Countries in North America · Countries in the EU

Frequently asked questions