August 25, 2026
We work with poster sizes in inches and centimeters every day. This guide gives you the exact CM measurements for every common poster format, including US standards and ISO A-series sizes used internationally.
Poster measurements in centimeters matter when you are working with international print shops, sourcing frames from non-US suppliers, or running campaigns outside North America. The US poster industry uses inches as the standard unit. But the rest of the world uses the metric system, and the ISO A-series sizes that go with it.
We run campaigns in the United States, but we work with brands and clients who operate globally. We have placed outdoor posters in New York, Los Angeles, Chicago, and Miami. We have also supported campaigns produced in Europe and shipped to the US. Converting between inches and centimeters is something we do regularly.
This reference guide gives you all the poster measurements you need in centimeters, alongside their inch equivalents and typical use cases. Keep it handy when you are specifying files, ordering print, or sourcing display hardware.
One inch equals exactly 2.54 centimeters. That means you can convert any inch measurement to centimeters by multiplying by 2.54. To convert centimeters back to inches, divide by 2.54.
For example: 24 inches x 2.54 = 60.96 cm. And 36 inches x 2.54 = 91.44 cm. So a 24×36 inch poster is 60.96 x 91.44 cm in metric.
When rounding for print specs, most shops round to two decimal places. Some round to the nearest millimeter (one decimal place in centimeters). Always confirm with your print shop how they want measurements expressed before submitting your file.
Quick Conversion Reference
1 inch = 2.54 cm. 10 inches = 25.4 cm. 12 inches = 30.48 cm. 18 inches = 45.72 cm. 24 inches = 60.96 cm. 36 inches = 91.44 cm. 40 inches = 101.6 cm. 48 inches = 121.92 cm.
| Poster Size (inches) | Width (cm) | Height (cm) | Common Use |
|---|---|---|---|
| 8 x 10 | 20.32 | 25.40 | Photography, small displays |
| 8.5 x 11 | 21.59 | 27.94 | Letter-size promotional sheets |
| 11 x 14 | 27.94 | 35.56 | Photography prints, indoor signage |
| 11 x 17 | 27.94 | 43.18 | Event flyers, small format outdoor |
| 12 x 18 | 30.48 | 45.72 | Mid-size promotional posters |
| 18 x 24 | 45.72 | 60.96 | Standard outdoor poster campaigns |
| 24 x 36 | 60.96 | 91.44 | Large outdoor, movie posters |
| 27 x 40 | 68.58 | 101.60 | Cinema one-sheet |
| 40 x 60 | 101.60 | 152.40 | Oversized outdoor campaigns |
The ISO A-series is the international standard for paper and poster sizes. These sizes are based on a consistent aspect ratio of 1:1.414 (the square root of 2). Each size is exactly half the area of the one above it. An A1 poster folded in half is A2. An A2 folded in half is A3. This system makes scaling and design reuse much simpler than the US system.
| ISO Size | Width (cm) | Height (cm) | Approx. US Equivalent |
|---|---|---|---|
| A5 | 14.85 | 21.00 | Between 5×7 and 6×9 |
| A4 | 21.00 | 29.70 | Close to 8.5×11 (letter) |
| A3 | 29.70 | 42.00 | Close to 11×17 (tabloid) |
| A2 | 42.00 | 59.40 | Close to 18×24 |
| A1 | 59.40 | 84.10 | Between 24×33 and 24×36 |
| A0 | 84.10 | 118.90 | Close to 33×47 |
When working with international print partners, specify the ISO size if possible. Most non-US print shops work with ISO sizes as their primary standard. Ordering an “18×24 poster” from a European print shop may result in confusion or a custom cut from A2 stock.
The B-series is another ISO standard, intermediate between A-series sizes. B-series posters appear in some European markets, particularly for theatrical and promotional displays.
| ISO Size | Width (cm) | Height (cm) | Common Use |
|---|---|---|---|
| B4 | 25.00 | 35.30 | Flyers, small posters |
| B3 | 35.30 | 50.00 | Event and promotional posters |
| B2 | 50.00 | 70.70 | Large promotional posters |
| B1 | 70.70 | 100.00 | Large outdoor posters, transit advertising |
| B0 | 100.00 | 141.40 | Very large display posters |
Field Note: Why We Still Specify in Inches for US Campaigns
All of our domestic US print partners work in inches. We specify everything in inches for US campaigns because that is the primary unit for American commercial printers. When we are producing files for international use or coordinating with overseas partners, we include both units in our spec sheets. It avoids reprints and wasted material.
When you send a print job, clear measurement specifications prevent errors. Here is how we specify poster measurements in our print briefs.
For US print shops, we use inches with decimal precision: “24.00 x 36.00 inches, portrait orientation.” We do not round. We state the unit explicitly. We also specify whether the dimensions are trim size (the final printed size after cutting) or bleed size (including the bleed extension).
For international or metric print shops, we convert to centimeters and specify to two decimal places: “60.96 cm x 91.44 cm, portrait.” We also include the ISO size if there is a close match, such as “closest to A1 (59.40 x 84.10 cm) but custom cut to 60.96 x 91.44 cm.”
Never assume the print shop will do the conversion for you. Measurement errors in poster printing result in the wrong output and additional cost. Be explicit. Be precise. Include units every time.
Not every campaign fits a standard size. When we plan campaigns in unusual spaces, such as irregular wall sections, construction barriers with existing fixtures, or custom retail displays, we need custom poster sizes.
For custom sizes, we measure the available wall space first, then subtract margins. We typically leave at least 5 cm of clear space around the outer edge of the poster to avoid mounting hardware, fixtures, or competing visuals. For a wall section that measures 90 cm wide by 120 cm tall, we specify a poster of 80 cm x 110 cm, centered on the available space.
Custom sizes cost more than standard sizes because they require custom cuts from standard stock. The less waste in the custom cut, the lower the cost. A 60 x 90 cm custom poster cut from standard 61 x 91 cm stock is nearly zero-waste. A 45 x 80 cm poster cut from 60 x 90 cm stock wastes a significant portion of the material.
Most design software accepts document size in centimeters or inches with an associated DPI setting. If your print shop needs a 300 DPI file for a poster measuring 60.96 x 91.44 cm (24×36 inches), here is how to calculate pixel dimensions.
First, convert cm to inches: 60.96 cm / 2.54 = 24 inches. 91.44 cm / 2.54 = 36 inches. Then multiply by DPI: 24 x 300 = 7,200 pixels wide. 36 x 300 = 10,800 pixels tall. So your design file should be 7,200 x 10,800 pixels at 300 DPI.
If your print shop specifies size in centimeters and DPI in their file requirements, the math is the same. Convert cm to inches first, then multiply by the required DPI. Design software like Adobe Illustrator and InDesign let you set document size in cm directly and will handle the pixel conversion internally.
Transit advertising posters have their own size specifications that vary by city, transit authority, and display type. Here are some common transit sizes and their centimeter measurements.
Always request the current spec sheet from the transit authority or display vendor. Sizes and bleed requirements change and vary by location. What works for a Los Angeles Metro placement may not match the specifications for a Chicago CTA placement.
An 18×24 inch poster is 45.72 cm wide by 60.96 cm tall. This is one of the most common outdoor poster sizes in the United States and is close to the ISO A2 size (42 x 59.4 cm). The A2 is slightly smaller than the US 18×24 format.
A 24×36 inch poster is 60.96 cm wide by 91.44 cm tall. This is slightly larger than the ISO A1 size, which is 59.4 x 84.1 cm. The 24×36 US format and the A1 ISO format are close but not interchangeable without custom cutting.
An A1 poster is 59.4 cm wide by 84.1 cm tall (594 mm x 841 mm). It is the standard large-format poster size in Europe and most of the world outside North America. In inches, A1 is approximately 23.4 x 33.1 inches.
An A2 poster is 42.0 cm wide by 59.4 cm tall (420 mm x 594 mm). It is the international equivalent closest to the US 18×24 inch format, though it is slightly smaller in both dimensions.
Multiply your inch dimensions by 2.54 to get centimeters. A 24×36 inch design becomes 60.96 x 91.44 cm. Then specify this to your international print shop as a custom size or confirm whether they can cut from their nearest stock size. Send the spec in centimeters to avoid ambiguity.
Neither is better. They serve different markets. The ISO system has the advantage of a consistent aspect ratio across all sizes, which makes scaling artwork up or down simple. The US system is what every commercial printer in North America stocks and quotes. Use whatever system your print partner works with.
For more on this, explore our guerrilla marketing services.
A B1 poster is 70.7 cm wide by 100 cm tall (707 mm x 1000 mm). It is larger than an A1 and is used in some European markets for large promotional posters. It is close in size to the US 27×40 one-sheet but noticeably taller.
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