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Input display resolution and diagonal size to instantly calculate PPI, total pixels, and dot pitch.
Enter screen resolution and diagonal size to view pixel density.
The box for your new monitor says "24-inch 1920×1080", but you care about how sharp it actually is. We use PPI (Pixels Per Inch) to answer that. The higher the PPI, the crisper the text edges and the sharper the image details. The calculator below gives you the answer in just three steps.
PPI calculation is based on the Pythagorean theorem. Diagonal pixels = √(Width Pixels² + Height Pixels²), then divided by the diagonal size in inches:
PPI = √(W² + H²) / D
Where W and H are the horizontal and vertical pixel counts, and D is the screen's diagonal length (in inches). The logic of this formula is simple: first calculate the total number of pixels on the diagonal, then average it out per inch.
Additionally, we automatically calculate the Total Pixels = W × H, and the Dot Pitch (the distance between the centers of adjacent pixels) = 25.4 / PPI (in millimeters). The smaller the dot pitch, the finer the display.
Main Example: 24-inch 1080p Monitor
Input: Width Pixels = 1920, Height Pixels = 1080, Diagonal Size = 24.
Calculation process:
Diagonal pixels = √(1920² + 1080²) = √(3,686,400 + 1,166,400) = √4,852,800 ≈ 2202.91 pixels.
PPI = 2202.91 / 24 ≈ 91.79.
Total Pixels = 1920 × 1080 = 2,073,600 (approx. 2.07 million).
Dot Pitch = 25.4 / 91.79 ≈ 0.277 mm.
Interpretation: This screen has a PPI of about 92, which is moderately sharp. It's fine for office work and watching videos, but you might notice slight jaggedness on text edges if you look closely. If you switch to a 27-inch monitor with the same resolution, the PPI will be lower (about 82), and the image will look rougher.
Comparison Example: 6.7-inch Phone, FHD+ vs QHD+
- FHD+ (2400×1080): Diagonal pixels = √(2400²+1080²) ≈ 2632.9, PPI = 2632.9/6.7 ≈ 393. Dot pitch ≈ 0.065mm.
- QHD+ (3200×1440): Diagonal pixels = √(3200²+1440²) ≈ 3510.8, PPI = 3510.8/6.7 ≈ 524. Dot pitch ≈ 0.048mm.
Interpretation: Upgrading from 393 PPI to 524 PPI is about a 33% increase. However, the human eye's perception limit for PPI at a normal viewing distance (about 30 cm or 12 inches) is around 300-450. Therefore, this 33% improvement won't be noticeable to most people unless they hold the screen very close to their eyes. Whether the extra cost is worth it depends on your specific use case.
