Display Tool
Screen Ruler
Measure elements on your screen in Pixels (px), Centimeters (cm), and Inches (in). Use the calibration tool for device-calibrated accurate real-world dimensions.
Digital Measurement Tool
⚠️ Accuracy Disclaimer: Without calibration, this tool assumes a standard desktop display. For high accuracy on laptops and smartphones, you must use the Calibration feature inside the tool. Your alignment directly affects accuracy.
How Digital Screen Measurement Works
Measuring physical objects on a digital display involves understanding the relationship between CSS Pixels and Device Pixel Ratio (DPI/PPI). Modern smartphones and Retina displays pack multiple physical hardware pixels into a single "software pixel" to make text look sharper. Because of this, 100 pixels on a 4K monitor will be physically much smaller than 100 pixels on an older 1080p monitor.
By default, web browsers assume a standard screen density of 96 PPI (Pixels Per Inch). If you are designing a website, the Pixel (px) unit is all you need. However, if you are trying to measure a physical screw, coin, or print-design in real-world centimeters or inches, the default math will be inaccurate on modern screens.
The Calibration Solution: To solve this, our tool includes a Calibration Mode. A standard credit card is exactly 85.6 mm (3.37 inches) wide worldwide. By resizing our digital box to match your physical card, the software instantly calculates the exact true Pixels-Per-Millimeter (mm/px) ratio of your specific screen, resulting in high-accuracy real-world measurements.
FAQ
Are the centimeters and inches accurate?
Without calibration, they are approximate values based on standard 96 PPI displays. For absolute accuracy on laptops, MacBooks, and smartphones, you must use the "Calibrate" button and match a credit card to the screen.
Will placing a credit card damage my screen?
No, standard plastic cards will not scratch glass displays. However, you should place it gently and ensure there is no sand or hard debris caught between the card and the screen.
How do I measure an element on another website?
Browser security prevents our tool from rendering over other browser tabs. To measure something on another page or application, take a screenshot of that application, open the image in a new tab, and use a dedicated screenshot measurement tool.