Paper sizes in centimeters: the ultimate guide to avoid mistakes

When it comes to printing, one of the most common and frustrating mistakes happens even before hitting "Print": choosing the wrong paper size. Whether it’s due to not knowing the exact measurements or confusing inches, centimeters, and pixels, this tiny detail can ruin an entire project.

In this definitive guide, brought to you by Sprintcopy, your trusted print shop in Barcelona, we’ll help you understand standard paper sizes in centimeters so your prints turn out just right—no surprises, no cropping, no awkward scaling.

Why is it so important to understand paper sizes?

It might seem like a minor technicality, but knowing paper dimensions is crucial if you're designing documents, printing graphics, or preparing files for professional printing. Not knowing exactly how big an A4 is or mistaking it for US Letter can lead to problems like:

Files that don’t match the final format 

Content being cropped or off-center 

Poor layout appearance 

Extra costs for last-minute adjustments

Avoiding these issues is as easy as understanding standard paper formats.

The A series: the most commonly used in printing

The A series, defined by international standard ISO 216, is the most widely used for stationery, office work, design, and print. It’s based on a consistent aspect ratio (square root of 2), which makes it easy to scale sizes (e.g., fold an A4 in half and you get an A5)

Here’s a list of the most common A sizes in centimeters:

  • A0: 84.1 × 118.9
  • A1: 59.4 × 84.1
  • A2: 42 × 59.4
  • A3: 29.7 × 42
  • A4: 21 × 29.7
  • A5: 14.8 × 21
  • A6: 10.5 × 14.8
  • A7: 7.4 × 10.5
  • A8: 5.2 × 7.4
  • A9: 3.7 × 5.2
  • A10: 2.6 × 3.7 

Tip

If you're sending your file to print, always include a 3 mm bleed around the edges to avoid cutting off key elements.

What about the B and C series?

While less well known, the B and C series also play a role in printing.

  • The B series provides sizes between A formats. It’s commonly used for posters, books, and special publications.
  • The C series is mainly for envelopes, designed to fit A-series paper sizes. 

Examples in centimeters:

  • B4: 25 × 35.3
  • B5: 17.6 × 25
  • C4: 22.9 × 32.4
  • C5: 16.2 × 22.9 

Centimeters vs. inches: don’t mix them up

If you work with software like Photoshop or Illustrator—or collaborate internationally—you’ll likely run into measurements in inches. Knowing how to convert between inches and centimeters is crucial when setting up your documents.

1 inch = 2.54 centimeters

For example:

  • A4 in inches ≈ 8.27 × 11.69
  • Letter (used in the U.S.) = 8.5 × 11 inches = 21.59 × 27.94 cm 

Tip

Letter ≠ A4. Many people confuse the two, but using the wrong one can ruin your layout if not adjusted properly.

Which paper size should I use for each project?

Choosing the right size depends not only on the standard but also on your project’s purpose. Here are a few examples:

Posters or large-format signage

A1, A2, or B1 for high visibility.

Tri-fold brochures

A4 folded or A3 for more visual impact.

Business cards

Custom size, usually around 8.5 × 5.5 cm.

Magazines or catalogs

A4 or B5, depending on editorial style.

Not sure what to use? Our team can help you find the best format based on your project and budget.

Avoid issues: how to properly prep your files

Before sending files to the printer, make sure they meet the following basic requirements:

Work in 300 dpi resolution 

Use exact size in centimeters (don’t scale at the last minute) 

Add bleed and safety margins 

Export as PDF/X ready for printing

Need help? Sprintcopy can guide you to the right format

At Sprintcopy, we’ve spent years helping clients print without hassle. Whether it’s a catalog, flyer, thesis, or large-format poster, we can advise you on which size to use, how to prepare your files, and what paper best suits your goals.

Contact us and we’ll help you avoid common mistakes and deliver a print result that exceeds expectations.