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Display geometry utility

Monitor Pixel Density / PPI Calculator

Calculate geometric pixel density, pixel pitch, and approximate active image dimensions from a display's pixel resolution and diagonal size. PPI describes how tightly pixels are packed; it is not an overall monitor-quality score.

Interactive calculation

Enter the display geometry

Enter the panel's horizontal and vertical pixel dimensions plus the active image diagonal in inches. The 2560 × 1440 at 27″ defaults are only a geometry example, not a monitor recommendation.

Use the active image diagonal when possible. The geometry assumes a flat rectangular pixel grid with square pixels. Bezels are not part of the calculated width or height.

Horizontal and vertical pixel counts must be positive whole numbers. Decimal diagonal sizes such as 31.5″ and 34.0″ are valid.

2,560 × 1,440 · 27″

108.79 PPI

Geometric pixel density from the entered resolution and active diagonal—not an overall monitor-quality score.

Pixel pitch
0.233 mm
Diagonal resolution
2,937.21 px
Active width
23.53″ · 597.7 mm
Active height
13.24″ · 336.2 mm

Geometry: diagonal pixels = √(horizontal² + vertical²), then PPI = diagonal pixels ÷ diagonal inches. Physical width and height are horizontal pixels ÷ PPI and vertical pixels ÷ PPI.

What PPI does not decide: panel technology, contrast, HDR, color accuracy, refresh rate, response time, viewing distance, visual acuity, or whether one monitor will look better to a particular person.

Geometry

Resolution and diagonal define the density

The pixel-grid diagonal is calculated with the Pythagorean relationship: √(horizontal² + vertical²). Dividing that diagonal pixel count by the active diagonal in inches gives pixels per inch.

Because the same square-pixel pitch applies along both axes, active width is horizontal pixels ÷ PPI and active height is vertical pixels ÷ PPI. No named aspect ratio such as 16:9 is assumed.

Pixel pitch is the reciprocal of PPI converted to millimetres: 25.4 ÷ PPI. NIST defines one international inch as exactly 25.4 mm.

Interpretation

Pixel density is one display property

PPI is a linear density—pixels per inch of display—not pixels per square inch. A smaller pixel pitch corresponds geometrically to a higher PPI for the same pixel grid.

Higher PPI does not by itself establish better panel technology, contrast, HDR, color accuracy, refresh rate, response time, scaling behavior, or the correct viewing distance.

Perceived sharpness also depends on viewing distance, eyesight, content, operating-system scaling, and rendering. This first version intentionally does not invent a “retina distance” or visual-acuity score.

References

Unit and display-density references

These sources support the exact inch-to-millimetre conversion and the display-industry use of PPI/pixel pitch. The calculator's Pythagorean geometry is shown directly on this page rather than delegated to a hidden formula library.

  1. 01 · NIST

    SI Units — Length: one international inch is exactly 25.4 mm

  2. 02 · EIZO

    4K monitor basics: pixel density in pixels per inch and pixel pitch

  3. 03 · EIZO

    27-inch 2560 × 1440 monitor specification with 109 ppi and 0.233 mm pixel pitch

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