On-Screen Ruler
Centimeters and inches, calibrated to your exact screen. Drag the ruler or move your pointer to measure. Nothing leaves your device.
Screen Calibration
Hold a credit card or ruler against your screen.
A standard credit card is exactly 85.6 mm (3.37 in) wide.
Adjust the DPI below until the reference bar matches your physical card.
px/in
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Position
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centimeters
Position
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inches
Position
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pixels
Accuracy note: This ruler relies on your browser's reported device pixel ratio and a user-set DPI value.
For best results, calibrate using a physical card or ruler above.
Screen rulers are accurate to within 1–2% once calibrated — sufficient for most everyday tasks.
Tip: On touch screens, tap and hold on the ruler to get the measurement at that point. Use the horizontal/vertical toggle for different measuring directions.
Tip: On touch screens, tap and hold on the ruler to get the measurement at that point. Use the horizontal/vertical toggle for different measuring directions.