1. An Introduction to ISO A and B Sizes

    Ever wondered why there are so many different paper sizes? The answer lies in a system called ISO 216, which defines the internationally recognized A and B series of paper sizes. This introduction will guide you through these common formats, helping you choose the right size for every project.

    The key to the ISO system is its elegant simplicity. Each size in the A series is exactly half the area of the next larger size, ensuring a consistent aspect ratio of the square root of 2 (approximately 1:1.414). This means you can easily fold or cut A4 paper in half to get A5, and so on, without any awkward trimming.

  2. A for All Occasion

    The A4 size (210 x 297 mm) is the undisputed king of the A series. It's the standard for business letters, reports, magazines, and countless other documents worldwide. Its smaller siblings, A5 (148 x 210 mm) and A6 (105 x 148 mm), are popular for brochures, flyers, and postcards, while A3 (297 x 420 mm) is perfect for posters and presentations.

    •  A Series Paper Guide
  3. A Paper Size
    Width (mm)Height (mm)
    A08411189
    A1594841
    A2420594
    A3297420
    A4210297
    A5148210
    A6105148
    A774105
    A85274
  4. The B Series

    While the A series focuses on everyday use, the B series offers intermediate sizes for specific purposes. B4 (250 x 353 mm) is often used for book printing, while B5 (176 x 250 mm) serves as a larger alternative to A5.

    •  B Series Paper Guide
  5. B Paper Size
    Width (mm)Height (mm)
    B010001414
    B17071000
    B2500707
    B3353500
    B4250353
    B5176250
    B6125176
    B788125
    B86288
  6. Photo Lab Sizes: A Different Story

    While the ISO system reigns supreme in the paper realm, photo labs operate with a slightly different set of standard sizes. These sizes are rooted in the history of film photography, where 35mm film produced negatives with a 3:2 aspect ratio. This ratio translated into common print sizes like 4 x 6 (102 x 152 mm) and 8 x 10 (203 x 254 mm), which closely approximate the 3:2 format.

    However, photo labs offer a wider range than just the 3:2 options. You'll find square prints (5 x 5, 8 x 8), panoramic sizes (4 x 12, 8 x 24), and even larger formats (16 x 20, 20 x 30) for those truly impactful shots. While not directly tied to the ISO system, these sizes have become familiar to photographers and consumers alike, offering flexibility for presenting photos in various formats.

    •  Acrylic - Photo - Glossy - Sizecomparison
  7. Photo Lab Sizes
    Inches (")
    Millimetres (mm)
    4 x 6
    102 x 152
    5 x 7
    127 x 178
    6 x 8
    152 x 203
    8 x 10
    203 x 254
    8 x 12
    203 x 305
    10 x 12
    254 x 305
    10 x 15
    254 x 381
    11 x 14
    279 x 354
    11 x 16279 x 406
    12 x 16
    305 x 406
    12 x 18
    305 x 457
    14 x 20356 x 508
    16 x 20
    406 x 508
    16 x 24406 x 610
    18 x 24457 x 610
    20 x 24
    508 x 610
    24 x 36610 x 914