How many pixels per cm does it take to design an inkjet billboard with PS?

When designing an inkjet billboard with Photoshop, the number of pixels per centimeter mainly depends on your design requirements and the DPI (dots per inch) of inkjet equipment.

Generally speaking, if you need very fine image quality, such as outdoor billboards or large billboards, it is recommended to use at least 30 pixels per cm. This is because in a high DPI inkjet device, each dot (pixel) will be converted into an actually printed ink dot. The higher the pixel, the better the detail and clarity of printing.

For example, if your inkjet device has a DPI of 300 DPI, you should use at least 300 pixels per centimeter. This is because 300 DPI means 300 dots per inch and 30 pixels per cm, so each pixel corresponds to one dot.

However, if your design does not require very high resolution, such as for small billboards or indoor displays, using 10 to 20 pixels/cm may be enough.

It should be noted that if your inkjet device supports a lower DPI (for example, 200 DPI), even if you use a higher pixel per inch, the printed effect may not be very good. Therefore, it is very important to choose suitable equipment and materials.

At the same time, you need to consider the actual size of billboards. If the billboard is large, even the density of 10 to 20 pixels may be enough. However, if the billboard is very small (for example, a few centimeters wide), you may need to use higher pixels per inch to maintain clarity.

Generally speaking, the best way is to contact your inkjet equipment supplier or printing factory to find out what the maximum DPI their equipment can support, and then choose the appropriate pixels per inch according to the design requirements and equipment capacity.