Calibrate

Place a real credit, debit, or ID card flat on the dotted strip below, then drag the right edge until the on-screen card matches your real card's width exactly.

KBT Measure CARD 85.6 MM Calibration card 54 mm
Width: 324 px = 85.6 mm = 3.785 px/mm = 96.2 DPI
Status: Using default 96 DPI (uncalibrated)
Tip: if the on-screen ruler doesn't match a real ruler, recalibrate with your card. Keep browser zoom at 100% or the scale will be off.

Ruler

Measure an object

Rest a small object on the ruler above, then drag markers A and B to its two edges. Its real size shows below — ideal for a screw, SIM card, ring, bead, or photo when no physical ruler is handy.

Measured size 50.0 mm 5.00 cm 1.97 in
Switch the ruler to Horizontal to use the measure markers.
⌨ Free Online Ruler by KeyboardTester.click