Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Acronyms, Wikipedia.




(1) (Points Per Inch, Pulses Per Inch) The measurement of mouse movement.

(2) (PPI) (Perceptive Pixel Inc.) See PixelSense.

(3) (Pixels Per Inch) The measurement of the resolution of a monitor or scanner. Earlier CRT screens measured around 96 ppi, while LCD screens on laptop and desktop computers today range from about 100 to 140 ppi. In order to display more information, tiny smartphone screens require higher resolution. For example, in 2007, Apple introduced the iPhone with 160 ppi. Three years later, the iPhone 4's Retina Display screen was 326 ppi. The HTC One smartphone came out in 2013 at 468 ppi.

Pixels and Dots
Pixels per inch (ppi) are the number of full pixels per inch on a screen, and each pixel on a color display comprises three or more subpixels, with some exceptions (see PenTile). Dots per inch (dpi) rates printer resolution, and the dots refer to the smallest element that is printed (see dpi).

How Pixels and Dots Relate
A digital image is measured in pixels. For example, a 600x300 pixel image has 600 horizontal pixels and 300 vertical. The way the image appears on screen and paper is determined by the ppi and dpi. On a 100 ppi screen, the image would be 6" by 3". Printed at 300 dpi, the standard for quality printing, the paper image would be 2" by 1". An 8x10" high-quality print would therefore require an image with a minimum resolution of 2400x3000 pixels. To view it end to end on screen, it has to be scaled smaller, because most monitors are not large enough. See dot pitch and RGB.

iPhone Pixels
High pixel density is why it is easy to read text on smartphones such as these. (Image courtesy of Apple Inc.)
References in periodicals archive ?
The court ruled that as she wasn't told about the huge commission taken from her PPI payment - 71% - she was mis-sold it.
Don't waste firms in a So, when I'm asked if PPI claims are just encouraging 'compensation culture', it's easy to disagree.
Augusto: 31% of the cohort received a likely unnecessary PPI prescription.
There was a pre-existing medical condition that made the PPI policy invalid.
PPI may have been mis-sold to you if it turns out that the policy is not appropriate for your needs.
In contrast to the CPI, the PPI does not currently have complete coverage of services.
According to the researchers, factors associated with discontinuing a PPI included change from a given NSAID to a COX-2 inhibitor (multivariate hazard ratio for PPI discontinuation = 2.
Some 209,000 of these complaints related to PPI, and if PPI were removed as a factor, complaints would have fallen 12 per cent.
This figure is up from 109,500 this financial year and more than double the 60,000 PPI cases resolved in 2010/11.
The report is expected to show that nearly 150 people a day have logged complaints about PPI in the three months to the end of June, up from 135 a day last year.
Many households facing sharply rising costs will arrange pounds 10,000 personal loans over five years in the next few months - and pay over the odds for PPI because they aren't paying attention.