Credit Card Size & Dimensions
The Credit Card is one of the most reliable reference objects for calibrating a screen ruler. With standard dimensions of 85.6mm x 53.98mm (8.6cm x 5.4cm / 3.37" x 2.13"), it provides a reliable size reference for screen calibration.
Credit Card Exact Dimensions
Millimeters
85.6 x 53.98 mm
Centimeters
8.6 x 5.4 cm
Inches
3.37 x 2.13"
Standard credit card (ISO/IEC 7810)
How to Calibrate with a Credit Card
- Open the screen ruler on your device and select Credit Card from the calibration panel.
- Place your credit card flat on the screen, aligning it with the on-screen outline.
- Adjust the calibration slider until the outline matches your credit card exactly.
- The calibration is saved automatically. You can now measure any object with the ruler and get accurate readings in centimeters, millimeters, and inches.
Why Use a Credit Card for Calibration?
Calibration is essential because every screen has a different pixel density (PPI). A pixel on a 6-inch phone screen is physically much smaller than a pixel on a 27-inch desktop monitor. By placing a known-size object on the screen, the ruler can calculate the exact physical size of each pixel and convert measurements accurately.
The Credit Card is an excellent calibration reference because its dimensions follow an international standard, making it consistent worldwide. Most people have one readily available.