Accurate Online Ruler

Author: Calculator Academy Team

Last Updated:

Online Ruler

Adjust the slider until the red line matches the width of a standard credit card.

Rotate the screen on mobile and refresh the page to properly calibrate.

If this ruler does not work, follow these steps:

  • Reload the page
  • Hit the load and calibrate button
  • Double-check the consistency
  • Calibrate with
  • Try incognito mode on your browser.

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How this ruler works

The ruler works by understanding your window size and pixel ratio and estimating the dots per inch(DPI) of the screen. It then dynamically creates the ruler with the inch marks and 8th-inch marks. If this does not seem accurate, then it could be due to some information blocking in your browser.

online ruler