PPI Calculator & Screen Size Converter

Calculate pixel density, physical screen dimensions, aspect ratio, unit conversions,
and viewing-distance pixel visibility from one display specification.

2Results

Pixel Density (PPI)

221 PPI

Pixels per inch

At 50 cm, individual pixels
are not likely to be distinguishable.The estimated retina threshold is about
34 cm for this display.

Physical Width
Physical Height
Diagonal Size
Aspect Ratio
Pixel Pitch
Screen Area

3Visual Representation

2560 px(11.56 in / 29.36 cm)

1600 px(7.22 in /
18.34 cm)

13.6 in
(34.54 cm)

4Viewing Distance Analysis

Viewing Distance

Pixels are not likely to be distinguishable
at 50 cm.Estimated retina threshold distance: 34 cm

Pixels visible
(closer)Pixels not visible
(farther)

34 cm
(retina threshold)50 cm
(your distance)

5Unit Converter

0.452

How It Works

View All Formulas →

Key Formulas

PPI (Pixel Density)

PPI = √(widthPx² + heightPx²)
diagonalInches

Physical Dimensions

widthInches = diagonalInches × widthPx / pixelDiagonal

heightInches = diagonalInches × heightPx / pixelDiagonal

Pixel Pitch

pixelPitchInches = 1
PPI

pixelPitchMM = 25.4
PPI

How to use this PPI calculator

Enter the display resolution, diagonal size, and your viewing distance.
Select the units that match your specifications, then calculate the display.
Use PPI, physical dimensions, the diagram, and viewing-distance analysis together.

Before you calculate: what to enter

Resolution width and height are the display’s native pixel dimensions.
Diagonal size is the physical corner-to-corner panel measurement.
Viewing distance is the approximate distance from your eyes to the screen.
Use positive values from the panel specification, not the browser-window size.

How to read the results

PPI describes physical pixel density. Physical dimensions use your diagonal and aspect ratio, while pixel pitch describes the size of one pixel. Viewing-distance analysis is a practical reference, not a vision test.

Useful ways to apply these numbers

Compare displays, check UI mockup dimensions, or convert px, pt, dp, rem, inches, and centimeters with the active PPI as context.

Formula and variables

PPI = √(widthPx² + heightPx²) ÷ diagonalInches. widthPx and heightPx are the display resolution in pixels; diagonalInches is the physical diagonal converted to inches.

Worked example

A 1920 × 1080 display with a 24-inch diagonal is about 91.79 PPI. Its calculated physical dimensions are about 20.92 × 11.77 inches.

Limitations and assumptions

PPI describes display pixel density, not printer DPI. The screen diagram is proportional rather than physically calibrated, and pixel visibility is a reference model affected by vision, contrast, scaling, zoom, and viewing conditions.

Frequently Asked Questions (FAQ)

Clear answers about pixel density, screen geometry, units, and the viewing-distance reference model.