DPI Calculator
Quickly calculate the Dots Per Inch (DPI) of any screen or display. Enter the resolution and screen size to find its pixel density.
Understanding DPI (Dots Per Inch)
Dots Per Inch (DPI), often used interchangeably with Pixels Per Inch (PPI), is a measurement of the pixel density of a screen or display. It tells you how many pixels are packed into a single inch of the screen. A higher DPI generally means a sharper, clearer image with less visible pixelation.
Key Factors Explained
- Resolution (Width & Height): The number of pixels that make up the display, expressed as width x height (e.g., 1920x1080). More pixels mean a higher potential for detail.
- Screen Size: The physical size of the screen, measured diagonally from corner to corner in inches.
A large screen with a low resolution will have a low DPI, and images may appear blurry or "pixelated." A small screen with a high resolution, like on a smartphone, will have a very high DPI, resulting in a crisp, "Retina"-quality display where individual pixels are invisible to the naked eye.
The Formula
The DPI calculation is a two-step process using the Pythagorean theorem to find the diagonal pixel count:
- Calculate the diagonal resolution:
d_p = √(w_p² + h_p²) - Calculate the DPI:
DPI = d_p / d_i
Where w_p is width in pixels, h_p is height in pixels, and d_i is the diagonal size in inches.
Frequently Asked Questions (FAQ)
What is a good DPI?
A "good" DPI depends on the device and its typical viewing distance. For smartphones held close to the face, a DPI of 300+ is considered excellent. For a computer monitor viewed from a couple of feet away, 110-140 DPI is very sharp. For a large TV viewed from across the room, the DPI can be much lower without a noticeable loss in quality.
How is DPI different from PPI?
Technically, DPI (Dots Per Inch) refers to the density of printed dots on paper, while PPI (Pixels Per Inch) refers to pixels on a screen. However, in common marketing and tech discussions, the terms are used interchangeably. This calculator measures PPI but uses the more common term, DPI.
Why is my phone's DPI so much higher than my monitor's?
Phones have small screens but very high resolutions (e.g., 2556x1179 pixels on a 6.1" screen), resulting in a high DPI. This is necessary because you hold the device much closer to your eyes, where you can perceive finer details. A large monitor has its pixels spread over a much larger area, so its DPI is naturally lower.
For a more in-depth guide, read our detailed article on this topic.