Screen Ruler

Measure anything on your screen by clicking and dragging. Switch between line mode for single distances and box mode for width, height, and diagonal measurements. Supports pixels, centimeters, and inches with DPI calibration.

050100150200250300350400450500550600050100150200250300350400

Click and drag to measure

How it works

Click anywhere on the measurement canvas and drag to draw a line or rectangle. The tool measures the distance in pixels by default, and can convert to centimeters or inches if you calibrate your screen's DPI.

Modes

  • Line — Measures horizontal distance. Good for quick width measurements.
  • Box — Measures a rectangular area, showing width, height, and diagonal.

DPI calibration

Pixel measurements are always exact. For accurate centimeter or inch measurements, you need to set your screen's DPI (dots per inch). The default is 96, which is standard for most desktop monitors. Retina/HiDPI displays typically use 192 or higher. You can find your actual DPI in your operating system's display settings or by measuring a known object on screen.