Enter the horizontal and vertical pixels, and the length and width of a screen into the calculator to determine the DPI.

DPI Formula

DPI stands for dot per inch, or in other words, pixels per inch. Therefore, DPI is a measure of total pixels per inch of screen. The end result of this is the following formula: 

DPI = [THP /TW + TVP / TL ] /2
  • Where DPI is the average dots per inch
  • THP is the total horizontal pixels
  • TW is the total width (in)
  • TVP is the total vertical pixels
  • TL is the total length (in)

To calculate DPI, divide the horizontal pixels by the total width in inches, add this result to the result of the vertical pixels divided by the height, then finally, divide this result by 2.

DPI Definition

What does DPI stand for? DPI is defined as the total number of dots per inch of an electronic screen such as a computer screen or phone screen. The higher the number of dots per inch, the higher the resolution of the screen.

Are DPI and PPI the same? Typically DPI (dots per inch), and PPI (pixels per inch) are considered the same and are often used interchangeably. DPI is more general since it uses dots per inch, however, in 99% of cases one dot is equal to one inch.

How to calculate DPI?

The following example problem uses the formula above to determine the dots per inch of a computer screen.

  1. First, determine the total number of horizontal pixels. From the manufacturing description, the screen in this example was found to have 1980 pixels horizontally.
  2. Next, determine the total number of vertical pixels. From the same documents, the vertical number of pixels is found to be 1080.
  3. Next, measure the horizontal width. The width of the screen is measured to be 16 in.
  4. Next, measure the vertical length. The vertical height is found to be 10 in.
  5. Finally, calculate the average DPI. Using the formula above, the average DPI is calculated to be (1980/16 + 1080/16) /2 = 115.875 DPI.

Additional Information

Can DPI be increased? A DPI can sometimes change under the settings of a device, but the maximum DPI the screen is rated for can never be increased once the screen is manufactured. This means that if set to the max by default, the DPI can only be decreased.

Does DPI affect file size? A higher DPI will lead to a higher file size because there are more individual data points, aka pixels, that the file needs to communicate with the device. Conversely, decreasing the DPI will decrease the file size, while also decreasing the resolution of the image or video.

Does DPI matter for digital art? In general, the DPI of a screen will limit the resolution that a person can view of a piece of digital art. In other words, even if the art is created and saved in a file rated at an average DPI of 200, a person can only view the art at the DPI at their screens maximum DPI.

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