INCHES

On-Screen Ruler

A calibrated ruler overlay — scaled to real-world size. Drag it anywhere, resize from the right edge.

Unit Mode
Screen Calibration
Most screens report 96 PPI via CSS — but your display's true pixel density may differ. Adjust until the ruler matches a physical ruler or card.
96 PPI

💳 Credit card trick: Hold a standard card (85.6 mm wide) against the bar below. Drag the slider until they match.

85.6 mm
Ruler Status

Drag the dark bar to reposition · Resize from the right edge