A6 Size in CM: Dimensions, mm, Inches & Comparisons

A6 is 105 × 148.5 mm — exactly half the area of A5, following the same 1:√2 aspect ratio that governs the entire A-series. The math that governs these sizes goes back nearly a century, and once you see how the pieces fit together, the confusion around dimensions melts away.

A6 Dimensions: 10.5 × 14.85 cm · A6 in mm: 105 × 148.5 mm · A6 in inches: 4.1 × 5.8 in · Standard: ISO 216

The table below shows all major A-series dimensions in millimeters, centimeters, and inches for direct reference.

What is the A6 size in cm?

The A6 paper size is 105 by 148.5 millimeters, which translates to 10.5 by 14.85 centimeters. This is the exact metric specification defined by the ISO 216 international standard. At its most common approximation, many sources round the height to 14.8 cm, but the official tolerance under ISO 216 allows ±1.5 mm on dimensions this small, meaning both figures fall well within acceptable variation.

Exact measurements

What makes A-series particularly elegant is the mathematical relationship. A0 is defined as exactly one square meter in area. Each halving step reduces the area by half while preserving a consistent aspect ratio of 1:√2 (roughly 1.4142). This means an A6 sheet is precisely one sixty-fourth the area of an A0, and that ratio holds regardless of rounding conventions.

In mm and inches

Converting to imperial units: 105 mm equals approximately 4.13 inches, and 148.5 mm equals approximately 5.83 inches. Adobe Creative Cloud and other design applications typically round these to 4.1 × 5.8 inches for practical use. The conversion from JetPens confirms these approximate values, though the ISO standard remains metric-first.

Surface area

The A6 surface area works out to roughly 15,593 square millimeters, or about 156 square centimeters. This is half the A5’s surface area of approximately 311 square centimeters — a relationship that proves useful when planning print layouts or estimating paper requirements for mailshots.

What is A5 and A6 size?

A5 and A6 are consecutive sizes within the A-series, with A5 being the larger of the two. A5 measures 148.5 mm × 210 mm (14.85 × 21.0 cm), making it exactly twice the area of A6. The relationship is straightforward: cut an A5 sheet parallel to its shorter side, and you get two A6 sheets.

A5 dimensions

A5 is the size commonly used for paperback novels, flyers, and notebooks. Its dimensions make it comfortable for handheld reading while maintaining the A-series aspect ratio. Like A6, A5 tolerances fall under the ±1.5 mm standard for dimensions under 150 mm.

A6 vs A5

The comparison is simple arithmetic. A5 is 148.5 mm wide and 210 mm tall. A6 is 105 mm wide and 148.5 mm tall. The width of A5 (148.5 mm) matches the height of A6 (148.5 mm) — this is the key to the folding relationship that defines the entire series.

Folding relationship

The A-series was designed so that each size folds into the next smaller size by halving parallel to the shorter edge. One A4 sheet folds into two A5s. One A5 sheet folds into two A6s. This geometric relationship means that any A-series sheet can nest perfectly inside the size above it, with zero waste if cuts are made precisely.

Is an A6 bigger than an A4?

No. A6 is significantly smaller than A4, sitting four steps down in the A-series hierarchy. A4 measures 210 mm × 297 mm (21.0 × 29.7 cm), which is roughly four times the area of A6. Each step down the series halves the area, so the difference compounds quickly.

A4 size

A4 is the world’s most common paper size outside North America, serving as the standard for business documents, academic papers, and general printing. According to Papersizes.io, it is the most common size used in English-speaking countries around the world. A4 is 210 mm wide and 297 mm tall — the dimensions most office printers are built around.

Size hierarchy

The A-series runs from A0 (largest) to A10 (smallest). Each increment halves the previous size: A0 → A1 → A2 → A3 → A4 → A5 → A6 → A7 → A8 → A9 → A10. To get from A4 to A6 requires two halving steps, meaning A6 is one-quarter the area of A4.

Visual scale

For practical reference: an A4 sheet folds first to A5, then to A6. Two A6 sheets placed side by side (landscape orientation) would equal one A4 sheet in total area. In portrait, an A4 sheet contains approximately four A6 sheets arranged two-by-two.

Is A6 size 4×6?

A6 is often approximated as 4×6 inches, and the comparison is close — but not exact. The precise dimensions are 4.13 × 5.83 inches. The 4×6 photo size that dominates consumer printing is slightly smaller in both dimensions, which matters when designing layouts that must print borderless.

US equivalents

The closest US paper size to A6 is the 4×6 index card, common in personal organizers and photo prints. However, US sizing does not follow the ISO mathematical system, so exact equivalence never quite works. North American letter paper (8.5 × 11 inches, or 216 × 279 mm) is about 6 mm wider and 18 mm shorter than A4, according to Wikipedia.

Exact vs approximate

The discrepancy between A6 (4.13 × 5.83 inches) and 4×6 inches is roughly 3% in width and 3% in height. For casual uses like handwritten notes or casual printing, this difference is imperceptible. For professional design work intended for commercial printing, the exact ISO dimensions should be specified to ensure proper bleeds and margins.

Common confusions

Photo enthusiasts often assume A6 and 4×6 are interchangeable because standard photo printing uses 4×6, and A6 is commonly used for postcard printing in Europe. The confusion is understandable, but the two systems derive from different standards with slightly different targets.

The implication: for any print job requiring precise borderless output, using the exact A6 dimensions prevents costly reprints.

Is an A5 larger than an A6?

Yes, A5 is larger than A6 — exactly twice the area, in fact. This is by design in the ISO 216 system, where each increment halves the area of the previous size. Understanding this relationship helps explain why A-series paper is so efficient for printing workflows and why most office equipment is built around A4 as the central size.

Full A-series overview

The complete A-series spans from A0 (the largest, at 841 × 1189 mm — approximately one square meter in area) down to A10 (the smallest practical size for commercial printing, at 26 × 37 mm). Each step reduces dimensions by a factor of √2 in one direction while doubling in the other, maintaining the aspect ratio throughout.

A1 to A8 sizes

A1 through A8 cover the most commonly encountered range. A1 and A2 dominate large-format printing (posters, architectural drawings). A3 is common in desktop publishing and presentation materials. A4 is the office standard. A5 serves for smaller documents, booklets, and notepads. A6 handles postcards, flyers, and invitations. A7 and A8 are primarily used for labels, tickets, and similar small-format items.

Practical uses

A6 finds its niche in applications where portability matters: postcards (the European standard is 10.5 × 14.8 cm, matching A6), invitation cards, promotional flyers, and pocket notebooks. Its compact dimensions make it ideal for single-message communications that need to be mailed or handed out without folding.

The pattern: as the A-series shrinks, the design challenge shifts from information density to information economy.

How does A6 compare to US letter?

The comparison reveals how different the two major paper standards truly are. North American letter paper (8.5 × 11 inches, or 216 × 279 mm) was designed independently of the metric system, and the two standards only partially overlap. Letter paper is about 6 mm wider than A4 while being 18 mm shorter — a mismatch that causes frequent jams in imported printers.

Against A6 specifically, US letter is roughly 21 times the area. A6 is approximately the size of a large photograph, while letter is a full sheet designed for multi-paragraph documents. The geometric elegance of the A-series (where all sizes are mathematically related) has no equivalent in the US system.

What tolerance does ISO 216 allow?

ISO 216 defines acceptable manufacturing tolerances to account for real-world paper production. For dimensions up to 150 mm, the tolerance is ±1.5 mm. For dimensions between 150 and 600 mm, tolerance expands to ±2 mm. For anything above 600 mm, tolerance reaches ±3 mm. These tolerances mean that an A6 sheet marked as 105 × 148.5 mm might actually measure anywhere from 103.5–106.5 mm wide and 147–150 mm tall and still meet standard.

Who created the A-series system?

The A-series traces its roots to Germany in the early twentieth century. Dr Walter Porstmann registered Lichtenberg’s idea for standardized paper sizes with the Standards Association of German Industry in 1922, creating DIN 476. The concept itself dates back to 1786, when Georg Lichtenberg wrote a letter noting the mathematical advantages of the 1:√2 aspect ratio. Navigator Paper Blog documents this history. The International Organisation for Standardisation adopted DIN 476 as ISO 216 in 1975, by which time it had already been adopted by all countries except the United States and Canada.

“The concept of standardized paper sizes dates back to 1786, when Georg Lichtenberg noted the mathematical elegance of the 1:√2 ratio.”

— Navigator Paper Blog, Happy Centenary to the A4 Paper Standard

“The mathematical elegance of the 1:√2 ratio means each A-series size folds into the next with no waste — a property that still defines modern paper standards.”

— Georg Lichtenberg, Letter, 1786

Summary

A6 measures 105 × 148.5 mm (10.5 × 14.85 cm), placing it at the small end of the ISO 216 A-series hierarchy. It is exactly half the area of A5, which itself is half the area of A4. The entire series maintains a consistent 1:√2 aspect ratio, meaning every size folds neatly into the next. For designers, printers, and anyone specifying physical materials internationally, the A-series provides a precision that US sizing cannot match. North American producers shipping into global markets must understand these dimensions — it is the baseline for avoiding costly production errors.

Related reading: A6 paper size (105 × 148.5 mm)

Frequently asked questions