Online Ruler — Actual Size
Choose your units and calibrate once for accurate on-screen measurements.
Units
Calibrate
Saved per screen. Current display: init
Method 1: Match this rectangle to your credit/debit card’s width, then press Save.
Target width: 85.60 mm • Current: 300px
The rectangle’s left and top edges are anchored. It never leaves the area.
Method 2: Enter your screen diagonal in inches. Fine-tune with nudges afterward.
Current scale: 3.780 px/mm