Online Ruler
Calibrate once, then measure anything on screen. Pick an edge, switch units with 1 2 3, and click the ruler to drop a marker.
Calibrate your screen
Pick the most convenient method — accuracy is highest with the credit card.
Auto-detect your device, or choose it from the list of popular models.
Enter your screen's diagonal size, printed on the box or in your device specs.
Detected resolution: —
Place any bank card, ID, or driver's license against the screen and drag the handle until the box matches its width exactly.
drag right edge →
85.6 mm
Calibration status
Not calibrated
- Method
- —
- 1 inch =
- 96 px
Shortcuts
- Inches / cm / mm123
- Dark modeD
- FullscreenF
- Clear markersC
Tip: keep browser zoom at 100% for an accurate ruler.