Posters & Pixel Dimensions

You should never design your poster purely by pixel dimensions. Design your poster using inches as the Knight ADRC poster service uses inches when printing. If you need assistance converting centimeters to inches, you can use this conversion website.

How pixel size relates to inches

Pixel dimensions convert to physical inches using DPI (dots per inch) with a simple formula:

Inches = Pixels/DPI

DPI tells you tightly packed the pixels are to one another. A high DPI number means that pixels are packed more densely. This creates a smaller physical size. Lower DPI means that the pixels are spread out. This creates a larger physical size.

Examples of how DPI affects physical size

Let’s assume you have designed a poster with the pixel dimensions of 3,600 wide by 1,200 high. Based purely on this information, there is no way to know the physical size because we don’t know the resolution (DPI).

Using the formula mentioned in the previous section, that 3,600 by 1,200-pixel poster at 300 DPI would be 12 inches by 4 inches.

At 150 DPI it would become 24 inches by 8 inches.

At 72 DPI, it grows to 50 inches by 16.7 inches.

Key takeaways

Never design a poster around pixel dimensions. Even if you know your DPI within the design program, the PDF may be generated at a different DPI. Always design your poster inches when printing in the United States.

Note that all of your embedded images should have a resolution (DPI) appropriate to the final printed size of the poster. This is especially true for situations where you are asking the printing service to enlarge the poster for printing. The more percentage it is enlarged, the higher the DPI your images should be. In most cases, images over 300 DPI are not necessary.