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Turn SCREEN to RULER

Make your screen a ruler.

Set your display size, choose a length, and preview it at a real-world scale.

Logical: 1440 × 900 · Physical: 1440 × 900 · DPR: 1

Display settings

Display size (inches)
Want to turn
Quick presets

Result

10.0 cm3.94 in
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Estimated calibration: 24.1 CSS px/cm · Use 100% browser zoom for the closest result.

How it works

A ruler tuned to your display.

Your monitor's diagonal and aspect ratio determine its physical width. The browser-reported screen width then gives us an estimated number of CSS pixels per centimeter.

That estimate turns your chosen length into an on-screen ruler. It is useful for quick comparisons, remote planning, and a better sense of scale.

FAQ

A useful scale, with limits.

How can a browser show a real centimeter?

After you enter the display diagonal and aspect ratio, the tool estimates your display's physical width, then maps that width to CSS pixels reported by the browser.

Why does browser zoom matter?

Zoom changes the relationship between CSS pixels and the physical pixels on your display. Keep zoom at 100% after calibrating for the closest result.

Is this accurate enough for manufacturing?

No. This is a convenient visual reference for everyday objects, not a measurement instrument. Verify critical dimensions with a physical ruler or calibrated device.