On-screen ruler
A literal ruler for your screen: metric on the left half, imperial on the right - each zero at its outer edge, so you can measure against either side. It calibrates itself from your screen's pixel density (96 × devicePixelRatio - an estimate, flagged as such); enter your display's real size for exactness. Click-drag to measure between two points.
100% private - runs in your browser No upload · No account
Click and drag on the ruler to measure between two points.
Reading
Re-infer or calibrate to read lengths. The ruler uses your browser's CSS pixels, so browser zoom scales it - keep zoom at 100% for real-world readings.