DPI vs PPI and how it affects your printing quality?

DPI vs PPI

DPI is an abbreviation from Dots-Per-Inch.

PPI is an abbreviation from Pixels-Per-Inch.

DPI vs PPI – sounds simple or confusing? Let’s figure out what DPI is and why it is important to understand this meaning for your stickers creation or wide format media printing .

When we speak about DPI, it refers mostly about resolution of the printing. Most of the printers (no matter home or enterprise, old or modern) print  by dropping the ink through the printhead nozzles. As result, printed image contains thousands of dots and the quantity of these dots is measured by DPIDPI measures a density of physical dots of an image on a physical entity, for example, on a sticker or poster.

On another hand,  PPI (pixels per inch) refers mostly to the digital world – images and photographs. Digital image has no dimensions in inches or millimetres but in pixels. PPI helps to instruct the printer in what size the image needs to be printer. As an example, your 4 megapixels camera produces the photo images as 2000 x 2000 pixels. If the printing is set as 200 PPI, then the physical printing output size will be 10 x 10 inches. For 500 PPI, size decreases to 4 x 4 inches. In first example, the photo will be bigger comparing to the second one, however at the close look, quality of the second print wins because more pixels are printed on the same square inch.

Source: Wikipedia

However it would be wrong to say 100 PPI = 100 DPI. Because to print one pixel of specific colour, a printer has to render few dots in order to mix few colours correspondingly and to achieve desired pixel colour (see an image above).

Viewing Distance defines DPI

After all, as when we know a little of theory, it starts being clear why it is so important to provide high resolution raster/bitmap image in order to get your stickers, posters or banners in best quality without blur (if you have vector image, then you eliminate all these headaches and here is why).

Source: http://support.rolanddga.com/

But how to know what image resolution would work for what vinyl sticker or banner size?

Should we always consider high DPI and, on the contrary, to never use low DPI? For small stickers – yes, in contrast, for wide format banners – no.

The rule of thumb is – closer view, higher DPI required. For this reason, the perfect DPI of your artwork mostly depends on how far away the artwork is from the viewers.

To demonstrate, here is a table which will give you a good understanding of DPI based on Viewing Distance:

Viewing Distance Min Resolution
0.25m  /  0.82ft 720 dpi
0.6m  /  2ft 300 dpi
1m  /  3.3ft 180 dpi
1.5m  /  5ft 120 dpi
2m  /  6.5ft 90 dpi
3m  /  10ft 60 dpi
5m  /  16ft 35 dpi
10m  /  33ft 18 dpi
15m  /  50ft 12 dpi
50m  /  160ft 4 dpi
60m  /  200ft 3 dpi
200m  /  650ft 1 dpi

For stickers, we usually recommend to upload the images of minimum 300DPI. In this case, the sticker won’t look blurry from average half-meter distance.

For posters or banners, it really depends on the viewing distance.

Calculate the right image size

Now, when you know your desired DPI based on Viewing Distance, how to find out the right pixels size of your image?

The formula is: width (in) x DPI = width (px). This formula is approximate, because DPI is not equal to PPI but it is quite close. Use this formula to make sure your print won’t be blurry and your sticker will look great!

Here are few examples:

Physical Print Size (inches) DPI Digital Image Size (pixels)
1 x 1 400 400 x 400
3 x 3 400 1200 x 1200
10 x 10 300 3000 x 3000
30 x 30 100 3000 x 3000

Summary

To figure out the right size of your file, use next steps:

  1. Figure out DPI by the Viewing Distance (use table above).
  2. Find out the physical size of your desired sticker, decal, banner or poster.
  3. Calculate the digital image size (use formula above).

Steps above will give you a high level of confidence that your printing won’t be blurry and will look great!

We hope that this little article clarified the things around DPI vs PPI and how to use them.

Now you are ready to order your stickers, decals, banners or posters!

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