Q: Is this ruler accurate to the actual size?

Yes. InchRulers.com provides an actual size ruler by calculating your device's DPI. Since every monitor is different, we highly recommend using a standard credit card for calibration to achieve 100% physical accuracy.

Q: How to calibrate the ruler?

Click the "Calibrate My Screen" button. Place any physical card (credit card, ID, or driver's license) on the screen and adjust the virtual box to match its edges. This synchronizes the software with your hardware's actual size.

Q: Can I measure in Millimeters?

Absolutely. Switch to CM / MM mode to view a metric ruler with precise millimeter markings. The Inch mode shows increments down to 1/16th of an inch with professional tick hierarchy.