What Means DPI?

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DPI stands for Dots per Inch and PPI stands for Pixels per Inch. On their own these terms mean very little and most people use the terms incorrectly. The 2 terms are mostly used when referring to a printed image.

 

Printing Photo
When printing a photo you are probably most concerned with the PPI. This actually allows you to determine how big you can print a specific image. The DPI is a measure of how many dots of ink an inkjet is capable of printing. Remember, a Pixel is potentially made up of millions of colors, but an inkjet printer has to mix the 3 or more inks for each pixel. So, a printer, to print at 300PPI would need to be able to print at least 900 DPI, assuming that each pixel is made up of 3 dots of ink (1 of each primary color). It is a bit confusing as most people say DPI when in fact they really mean PPI.

For example, a printed photo at 300 PPI is a High resolution image that will show a lot of fine details. A photo less than 300 PPI will show less details in print, where more than 300 PPI will not greatly improve the quality.

 

Computer Screen
A Computer screen typically displays at 96 PPI and it is a trade off between providing the best possible quality vs. the price. To make a computer screen with a higher pixel density is very expensive.

The DPI information within an image is only used when it comes to printing out a picture because as we mentioned a computer screen displays in pixels and not inches. On a screen you get just the pixels at the screen resolution of 96PPI.

 

Tips: Get to know about Pixels here.
How to Resize Image for Printing?

 

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