How to calculate PPI
PPI is calculated using the diagonal pixel resolution and the physical diagonal size of the display in inches.
The pixel width and height describe the display resolution. The physical diagonal describes the actual screen size rather than its pixel dimensions.
PPI calculation example
A 1920 × 1080 display has about 2,203 diagonal pixels. On a 24-inch screen, that produces approximately 91.79 pixels per inch.
The same resolution on a smaller physical screen has a higher PPI, while the same resolution on a larger screen has a lower PPI.
What is pixel pitch?
Pixel pitch is the approximate physical spacing represented by one pixel. The calculator converts PPI into millimeters per pixel.
A higher PPI therefore produces a smaller pixel pitch when the pixels are arranged at the same physical scale.
PPI vs. resolution
Resolution alone does not tell you pixel density. A 1920 × 1080 resolution can appear on displays with very different physical sizes.
PPI combines both pieces of information: pixel resolution and physical screen size.
PPI vs. DPI
PPI is commonly used for pixels on digital displays. DPI means dots per inch and is commonly associated with printing or physical output.
The terms are sometimes used loosely, but they describe different kinds of density.
Pixels per centimeter
The calculator also reports pixels per centimeter. Since one inch equals 2.54 centimeters, PPI can be divided by 2.54 to find pixels per centimeter.
Calculating physical screen width and height
The resolution determines the screen's pixel aspect ratio. Combined with the diagonal measurement, that ratio can be used to estimate physical screen width and height.
These dimensions describe the rectangular display area implied by the entered resolution and diagonal. Bezels, casing and device dimensions are not included.
Aspect ratio and megapixels
The calculator simplifies the pixel width and height into an aspect ratio such as 16:9. Total pixel count is also shown in megapixels.
For more ratio calculations, use the Aspect Ratio Calculator.
The calculation assumes the entered resolution covers the entered rectangular display diagonal. Manufacturer specifications can differ for unusual display shapes, cropped active areas or other hardware details.
Frequently asked questions
What does PPI mean?
PPI means pixels per inch. It measures the number of display pixels across one physical inch.
Is higher PPI always a higher resolution?
Not necessarily. PPI depends on both resolution and physical screen size, so two displays with the same resolution can have different PPI values.
Can I enter screen size in centimeters?
Yes. Select centimeters and enter the physical diagonal in centimeters. The calculator converts it internally before calculating PPI.
What is pixel pitch?
Pixel pitch is the physical distance represented by one pixel. This calculator reports it in millimeters.
Does PPI tell me image quality?
PPI describes pixel density, but perceived image quality also depends on viewing distance, display technology, source content and other factors.
Using this calculator effectively
The PPI Calculator finds display pixel density from pixel resolution and physical diagonal size. It also reports pixel pitch, pixels per centimeter, megapixels, aspect ratio and estimated physical screen dimensions.
Common uses
- Comparing pixel density between monitors, laptops, phones, tablets and other displays.
- Finding pixel pitch from a known resolution and physical screen diagonal.
- Estimating physical screen width and height from diagonal size and resolution aspect ratio.
Tips for a better estimate
- Enter the actual pixel resolution of the display rather than a scaled operating-system resolution.
- Use the physical display diagonal, not the overall device or casing size.
- Remember that PPI measures pixel density only and does not by itself determine perceived display quality.
Related calculations
Print Size Calculator · Screen Size Calculator · Aspect Ratio Calculator