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Screen Size / PPI Calculator

Enter any three of width, height, diagonal, and PPI to solve for the rest — and compare two screens side by side.

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Screen A
—Width (px)
—Height (px)
—Diagonal (in)
—PPI
—Aspect ratio
—PPD (at distance)
Screen B
—Width (px)
—Height (px)
—Diagonal (in)
—PPI
—Aspect ratio
—PPD (at distance)
Fill in Screen A and Screen B to compare their pixel density.

About this tool

PPI (pixels per inch) is the diagonal resolution in pixels divided by the diagonal size in inches: diagonal_px = √(width² + height²), then PPI = diagonal_px ÷ diagonal_in. Fill in any three of width, height, diagonal, and PPI for a screen and the fourth is solved for automatically — useful when a spec sheet gives you PPI and diagonal but not the exact pixel count, or vice versa.

PPD (pixels per degree) additionally accounts for viewing distance — it's what actually determines whether individual pixels are visible to your eye, since a lower-PPI TV viewed from across a room can outresolve a higher-PPI phone held at arm's length. It's approximated with PPD ≈ PPI × distance × π ⁄ 180, matching the formula used by most "retina display" calculators.

Nothing you enter here is sent to a server — the entire tool runs as JavaScript in your browser tab.

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