About this website
Online Ruler provides a calibrated ruler and screen measuring guides for real objects and uploaded images. Start by calibrating the display with a known reference so that the on-screen units match your physical screen. Then read measurements in centimeters, millimeters or inches. Use the Screen Ruler's X/Y guides to check width, height and alignment, or open a larger fullscreen measuring area. You can place a small object against the screen or upload an image to measure and mark dimensions. Keep the display calibration appropriate to the screen you are using. The product also includes a quadrant layout, concentric circles, a tape-measure workflow and a protractor. These views support different tasks, such as locating a center, comparing radii and diameters, or exploring an angle. Online Ruler is useful for quick size references, drawings, product photos and teaching measurement concepts.
Key features
- Calibrate the ruler to match your display
- Measure using centimeters, millimeters or inches
- Inspect images at actual size for measurement
- Use a protractor to measure angles
Who is this website for?
Students, designers, makers and anyone who needs to measure small objects or inspect an image using an on-screen ruler.
What can visitors do here?
Calibrate the ruler to your display, place a small object against the screen and read its approximate length in centimeters or inches.
What makes it different?
Pairs display calibration with physical units, image measurement and a protractor in one browser-based measuring tool.
