What Are the Dimensions of an A1 Poster | American Guerrilla Marketing

The A1 poster is the workhorse of large indoor printing in the international market. If you are working with European vendors, ordering prints from an international print-on-demand service, or designing for a market outside the US, you will encounter A1 size constantly. Here is everything you need to know about it.

The A1 poster measures exactly 594 millimeters wide by 841 millimeters tall. In inches, that is approximately 23.4 inches by 33.1 inches. In centimeters, it is 59.4 x 84.1 cm. These are the exact dimensions set by the ISO 216 international paper standard.

The ISO A-Series: Where A1 Comes From

The ISO 216 standard defines a family of paper sizes called the A-series. The largest in common use is A0, which has an area of exactly one square meter. Each subsequent size in the series is half the area of the one before it. A1 is half of A0. A2 is half of A1. And so on.

All sizes in the A-series share the same aspect ratio: 1:1.414 (the square root of 2). This mathematical relationship means every size scales perfectly into every other size without any cropping or distortion. An A2 design scaled up 141.4% becomes an A1. An A1 scaled down to 70.7% becomes an A2.

This is the key advantage of the ISO system over the US system. US poster sizes (11×17, 18×24, 24×36) do not share a consistent ratio, so scaling between them always requires layout adjustments.

A1 Dimensions in Every Unit of Measurement

Note that the pixel dimensions at 300 DPI are very large. An A1 poster at 300 DPI weighs in at nearly 70 megapixels when saved as an uncompressed image. That is a big file. For most large-format print applications, 150 DPI at final output size is sufficient and produces much more manageable file sizes.

DPI Guidance for A1 Posters
If the poster is viewed from less than 3 feet (close inspection), use 300 DPI. If it is displayed on a wall and viewed from 6 to 15 feet, 150 DPI is fine. For large-format prints viewed from 15+ feet, 100 DPI is acceptable. More DPI does not always mean better results, it means bigger files and slower workflows.

How A1 Compares to US Poster Sizes

If you are based in the US and used to working with US standard sizes, here is how A1 stacks up:

A1 sits between the US 18×24 and 24×36. It is closer in area to a 24×36 than to an 18×24. The proportions are similar but not identical. A 24×36 poster design does not map cleanly onto an A1 document without some adjustment.

When to Use A1 vs. 24×36

This is the practical question for anyone working across both US and international markets.

Use A1 When:

• Your print vendor is based in Europe, the UK, or another ISO-standard country
• You are designing for an international brand campaign with prints across multiple countries
• Your display hardware or frames are specified in A1 (common in European retail chains)
• You are working in a print environment that defaults to A-series sizes (InDesign EU templates, etc.)
• Your content needs to scale cleanly to A2 or A0 for different applications

Use 24×36 When:

• You are working with US print vendors
• Your frames or display hardware are sourced domestically
• Your campaign is US-only
• You need off-the-shelf framing that you can source at US home goods stores
• Your print partner quotes on 24×36 by default

Mixing A1 and 24×36 in the Same Campaign
Do not mix A1 and 24×36 within the same campaign unless you have separate display hardware for each format. The sizes are close but not interchangeable. An A1 print installed in a 24×36 frame will show gaps. A 24×36 print in an A1 frame will be too large. Pick one and commit.

The Full ISO A-Series Poster Size Chart

Understanding A1 is easier when you see it in context with the full A-series family.

Setting Up an A1 Poster File

Here is the exact setup for an A1 poster file in common design applications:

In Adobe InDesign

• Document size: 594 mm x 841 mm
• Bleed: 3mm on all sides (0.118 inches)
• Color mode: CMYK
• Export as PDF/X-1a or PDF/X-4

In Adobe Illustrator

• Artboard size: 594mm x 841mm
• Add bleed on export: 3mm
• Color mode: CMYK document mode

In Canva

• Custom size: 594mm x 841mm or 23.39 in x 33.11 in
• Note: Canva exports in RGB. Convert to CMYK if your printer requires it
• Download as high-quality PDF

Image Resolution Guidelines

• Minimum acceptable: 100 DPI at final print size
• Recommended for most applications: 150 DPI
• Maximum useful: 300 DPI (for close-inspection display)
• At 300 DPI, the final image canvas is 7016 x 9933 pixels

A1 Poster Paper Stock Options

The paper stock you choose affects how the A1 poster looks and holds up in use. Common options include:

135 gsm Silk / Gloss

The most common stock for marketing and event posters. Bright colors, sharp image reproduction. Good for indoor use. Not water-resistant without lamination.

170 gsm Gloss

Heavier, more premium feel. Holds up better for display use where the poster will be handled frequently. A popular choice for exhibition and gallery contexts.

200 gsm or 250 gsm Card Stock

Thick, rigid-feeling poster. Used for premium art prints, collector items, and high-end brand campaigns. More expensive, but the tactile quality communicates premium positioning.

Matte Coated Stock

A flat finish with no glare. Reads well under fluorescent lighting where gloss would create reflections. A good choice for office lobbies, galleries, and conference displays.

Outdoor / Synthetic Stock

Waterproof polypropylene or polyester media. Used for any outdoor application or anywhere moisture is a concern. Durable and tear-resistant.

A1 Poster Dimensions FAQs

Is A1 a good size for an event poster?

Yes. A1 is an excellent size for indoor event posters. It reads well from about 10 to 15 feet away, which suits most venue and lobby applications. For outdoor events and street-level placement, the US 24×36 may be more practical since it is stocked at US print shops by default.

Frequently Asked Questions