How to Calibrate and Use Online Ruler for 1:1 Accuracy
Measuring objects on a screen can be tricky because different monitors have different resolutions and scaling settings. Online Ruler solves this by allowing you to calibrate your screen using real-world objects.
Follow this guide to get started.
Step 1: Enter Calibration Mode
After installing the extension, click the Online Ruler icon in your browser toolbar. In the popup that appears, click the "Enter Calibration Mode" button.
Step 2: Align with a Physical Object
Calibration is the key to 1:1 accuracy.
- Select a reference object from the list (e.g., a Credit Card, A4 Paper, or a 1 Yuan Coin).
- Take the physical object and hold it up against your screen.
- Use the slider (or the +/- buttons for 1-pixel precision) to adjust the size of the red box on your screen until it matches the physical object exactly.
Once aligned, click "Save and Start Measuring". Your screen's PPI (Pixels Per Inch) is now calculated and saved.
Step 3: Start Measuring
You can now use the ruler in two ways:
- Independent Window: Click "Open Independent Ruler Window" for a clean, resizable ruler that stays on top. You can toggle between horizontal and vertical modes.
- Web Overlay: Click "Add Ruler to Current Page" to inject a ruler directly onto the website you are viewing. This is perfect for measuring elements within a design.
Step 4: Adjust Zero Point (Optional)
If the object you are measuring is partially blocked or if you need a specific starting point, use the "Zero Point Offset" slider in the popup. This allows you to set a custom starting gap in millimeters.
Pro Tips
- Wood Texture: The ruler uses a realistic wood grain design to ensure that the scales remain clear and easy to read.
- Full-Edge Resizing: In overlay mode, you can drag anywhere on the edges of the ruler to resize it—no need to look for a tiny handle in the corner!
- Privacy: All your calibration data is stored locally. We never track what you measure.
Happy measuring! 📏