A5 Size in cm: Exact Dimensions, Comparisons & Uses

You reach for a sheet of paper to jot down a note, print a leaflet, or start a planner — and suddenly the size matters. A5 sits right in the middle of the A-series family, bigger than a postcard but smaller than a letter; this guide explains its exact dimensions, comparisons to A4 and A6, and why its half-size geometry is so useful.

A5 dimensions in cm: 14.8 × 21.0 cm · A5 in mm: 148 × 210 mm · A5 in inches: 5.8 × 8.3 in · Half of A4: Yes · A5 area: 310.8 cm² · Aspect ratio: 1:1.414 (√2:1)

“The international standard for A-series paper sizes defines A5 as 148 mm × 210 mm.” — ISO 216 standard

The snapshot confirms A5 sits firmly within the ISO 216 standard.

The table below summarises the key A5 specifications.

“Printer guides sometimes list A5 as 148.5 × 210 mm for cutting tolerance.” — Brother UK support

Eight measurements, one pattern: every A5 dimension flows from the √2:1 ratio, meaning the sheet keeps its proportions when halved.

What is size A5 in cm?

• A5 measures exactly 14.8 × 21.0 cm — that’s 148 × 210 mm (Adobe Creative Cloud).
• The same sheet is 5.8 × 8.3 inches (Neenah Paper).
• Its area is 310.8 square centimetres — about 0.33 square feet.
• The aspect ratio is always 1:1.414 (√2:1), the same as every other A-series size (Paper Sizes).

A5 dimensions in millimeters and inches

• Millimeters: 148 × 210 mm — the ISO 216 standard (Paper Sizes).
• Inches: 5.8 × 8.3 in (rounded to one decimal).

A5 area and aspect ratio

A5’s area of 310.8 cm² makes it one quarter of A3 and half of A4. The aspect ratio means you can double the paper size and keep the exact same shape — no wasted margins when scaling.

The pattern is clear: every A5 measurement derives from the √2:1 ratio.

Is A5 exactly half A4?

Yes — A5 is precisely half the area of A4. The math is straightforward.

• A4 dimensions: 21.0 × 29.7 cm (Paper Sizes).
• Halving A4 lengthwise (21.0 cm becomes 14.8 cm, 29.7 cm becomes 21.0 cm) gives you A5.
• The A series uses a √2:1 ratio so that halving preserves the shape (Wikipedia).

Mathematical relationship between A4 and A5

Every step up or down the A series doubles or halves the area. So A4 = 2 × A5, A5 = 2 × A6, and so on. The dimensions come from the fixed width-to-length ratio of √2:1.

Why the A series works with halving

The beauty of the √2:1 ratio: when you cut a sheet in half, the two smaller sheets have the same proportions as the original. This is why A5 makes sense as a common size — it’s a direct fraction of A4 without weird cropping.

The halving principle makes the A series uniquely practical for scaling designs.

Are A4 and A5 the same size?

No. A4 is noticeably larger. Here’s the real-world difference.

• A4: 21.0 × 29.7 cm — roughly the size of a typical laptop screen (Snap Print).
• A5: 14.8 × 21.0 cm — about the size of a large notebook or paperback book (Snap Print).
• Two A5 sheets side by side equal one A4.

Key differences between A4 and A5

A4 and A5 differ in practical ways that affect everyday use.

Three comparisons, one pattern: A4 is for desk work, A5 is for portable tasks.

When to use A4 vs A5

• Use A4 for formal documents, invoices, and anything that requires full-page reading.
• Use A5 for handouts, pocket planners, invitations, and any situation where the reader carries the sheet.

The choice between A4 and A5 comes down to where the paper is used.

What is A1, A2, A3, and A4?

The full A-series ranges from A0 (a huge poster) down to A6 (a postcard). Each size is half the previous one. The choice between A4 and A5 comes down to where the paper is used, and you can learn more about the ${iPhone 12 Pro gebraucht Wert} in this guide. iPhone 12 Pro gebraucht Wert

• A0: 84.1 × 118.9 cm
• A1: 59.4 × 84.1 cm
• A2: 42.0 × 59.4 cm
• A3: 29.7 × 42.0 cm
• A4: 21.0 × 29.7 cm
• A5: 14.8 × 21.0 cm
• A6: 10.5 × 14.8 cm

All dimensions from Paper Sizes.

Complete list of A-series sizes from A0 to A6

How each size relates to the next

Each size is exactly half the area of the previous. So A1 is half of A0, A2 is half of A1, and so on. The dimensions always follow the √2:1 ratio.

Each step in the A series halves the area of the previous size, maintaining the same proportions throughout.

Is A5 or A6 bigger?

A5 is larger than A6. Think of a standard paperback book (A5) versus a postcard (A6).

• A5: 14.8 × 21.0 cm — 310.8 cm² area.
• A6: 10.5 × 14.8 cm — exactly half the area of A5 (Avery).
• A6 dimensions in inches: 4.1 × 5.8 in (Paper Sizes).

Size difference between A5 and A6

A5 is twice the area of A6. That extra 10.5 cm in height makes it usable for writing full sentences, while A6 is better for short notes or index cards.

Common uses for A5 and A6

• A5: notebooks, diaries, flyers, small calendars, pocket sketchbooks.
• A6: postcards, greeting cards, recipe cards, small flyers, invitation inserts.

The size difference determines their best use cases: A5 for writing, A6 for short notes.

Confirmed facts

• A5 dimensions are 14.8 × 21.0 cm (ISO 216 standard) — Adobe Creative Cloud
• A5 is exactly half of A4 in area — Wikipedia
• A5 aspect ratio is √2:1 — Paper Sizes
• A5 dimensions in inches: 5.8 × 8.3 — Neenah Paper
• A6 is half the area of A5 — Avery

All confirmed facts align with the ISO 216 standard.

Summary

A5 size in cm — 14.8 × 21.0 — is no arbitrary number. It emerges from the elegant halving principle of the ISO 216 standard, giving you a sheet that fits neatly between a desk-friendly A4 and a pocket-sized A6. For anyone buying notebooks, planning a print run of flyers, or setting up a home office, the choice between A4 and A5 comes down to portability versus page space. A5 wins when the paper has to travel. For UK and Ireland buyers who often face both metric and imperial confusion, the rule is simple: if you want a manageable size that’s still big enough for real writing, reach for the 14.8 × 21.0 cm sheet — that’s your A5.

Related reading: 5 8 in CM – The Exact Conversion to 172.72 Centimeters · Queen Size Bed Dimensions: Ireland, UK & US Sizes Guide

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