OG Online Ruler

What is OG Online Ruler?

OG Online Ruler is a free online measuring tool that turns your screen edge into a real ruler. It supports centimeters, millimeters, inches, and pixels, so you can check small objects, layouts, and screen spacing without downloading anything. You can place rulers on any edge of the screen, add guides, use a crosshair, and measure between two points. The app also includes several calibration options, like automatic device detection, selecting a known device, entering screen diagonal size, or matching a standard bank card. Calibration stays on your device, and nothing is uploaded. It is built for quick, private, and accurate measurements directly in the browser.

Key features

• Supports centimeters, millimeters, inches, and pixels.
• Places rulers on top, bottom, left, or right.
• Offers auto-detect, device, diagonal, and card calibration.
• Stores calibration locally in your browser only.
• Includes guides, crosshair, and two-point measurement box.
• Works in fullscreen with keyboard shortcuts for speed.