How do I calibrate the online ruler so it shows real sizes?
Hold any bank card against the screen on the online ruler, resize the outline until it matches the card exactly, and press Save calibration. Or type your screen size in inches.
Step by step
- Open the online ruler and choose With a bank card.
- Hold a card (debit card, ID or loyalty card – all 85.60 × 53.98 mm) flat against the top-left of the outline.
- Drag the slider, or use − and +, until the outline matches the card.
- Press Save calibration.
- Place the object at 0 and read the length. Click or drag on the ruler to place a marker.
Questions and fixes
The measurements are wrong now
Recalibrate if you change the browser zoom, move the window to another screen, or use another device.
I don’t have a card
Choose With your screen size and type the diagonal in inches (for example 15.6). It is less accurate and needs the browser zoom at 100%.
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