Understanding your result
PPI counts pixels along one physical inch. Pixel pitch is the distance between adjacent pixel centres under a square-pixel model. Active width and height exclude the bezel and stand.
For image dimensions on paper rather than a physical screen, use the Print Size Calculator .
The formula
The pixel grid diagonal follows the Pythagorean theorem. Dividing its pixel length by the physical diagonal establishes one common pixel scale. Dividing each pixel dimension by that scale then gives the active screen dimensions in inches, converted here to centimetres.
Worked example
A 1,920 by 1,080 display with a 24-inch diagonal has a pixel diagonal of about 2,202.907. Dividing by 24 gives about 91.788 PPI and a pixel pitch of approximately 0.2767 mm. Doubling both pixel dimensions at the same size doubles PPI.
How to use this calculator
- Enter the panel’s native horizontal and vertical pixel counts.
- Enter the diagonal of its active display area in inches.
- Read PPI and pitch, then use the table to compare the same resolution at nearby sizes.
Native pixels and interface scaling
Operating systems can render an interface at a scaled logical resolution. That setting changes the size of interface elements, not the physical number of pixels on the panel. Use the native hardware specification for this calculation. Browser CSS pixels and Android density-independent pixels are layout units and need not match individual panel pixels.
Density is only one part of appearance
Viewing distance, contrast, subpixel structure, image processing, and source resolution affect how a screen looks. PPI alone cannot certify that a display is sharp enough for every viewer or task. A rounded manufacturer diagonal also limits the precision of the result. This model assumes a rectangular active area and square pixels; it does not analyze unusual pixel geometries or curved-surface measurements.
Assumptions & limitations
What this calculation assumes
- The panel has a rectangular grid of square pixels and a matching active-area diagonal.
What to keep in mind
- No visual-acuity threshold, device database, print-quality rating, or subpixel rendering simulation.
Common questions
Is screen PPI the same as printer DPI?
No. PPI describes image or display pixels; printer DPI describes device marking dots. Their numerical values are not automatically interchangeable.
Will changing desktop scaling alter PPI?
No. Physical density remains fixed unless the display hardware or measured active size changes.