Online Ruler, Calibrated to Your Actual Screen

Why it surfaced

It tackles the deceptively tricky problem of screen scale: calibration can use a display model, advertised screen size, or a reference object such as a bank card or coin. The tool also lets users drag a ruler anywhere, measure diagonals, and calculate distance and angle between two clicks.

A free browser ruler for measuring in millimetres, centimetres, decimal or fractional inches, points, picas, and pixels.