Ruler On Screen

What is Ruler On Screen?

Ruler On Screen displays a calibrated ruler directly on your screen for measuring real-world objects. Calibrate it using a known reference (like a credit card or coin), then measure in centimeters or inches. Works on any screen size.

How to use

1. Calibrate the ruler by placing a credit card (85.6mm) or other standard object against the screen and adjusting the scale to match.
2. Switch between centimeters and inches using the unit toggle. The ruler adjusts in real time.
3. Place objects against your screen and read measurements directly from the ruler markings.

Result

You need to measure a USB connector but don't have a physical ruler. Open the tool, calibrate using your credit card width (85.6mm), then hold the USB connector against the screen — it reads 12mm, confirming it's a standard USB-A port.

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