Online Protractor | Angele Protractor |Measure Angles on Images

Reference Tools

Base Rotation

Instrument Settings

Scale Radius

Position X/Y

Snap Angle

Calculated Angles

Click on the image to drop an angle marker.

User Guide & FAQ

How to align with a vertex?

Drag the red center point directly with your mouse. For micro-adjustments, use Arrow Keys on your keyboard to move the center 1px at a time.

How to measure the slope of a line?

Upload your image, move the center to one end of the line, and click to drop a marker. The "Base Rotation" field can also be used to align the zero-degree mark with any reference surface.

Measurement Accuracy

The tool supports 0.1° precision. Use the Mouse Wheel to enlarge the protractor for more detailed scale readings.

Privacy & Security

This is a client-side tool. Your images are never sent to our servers. All calculations and rendering happen instantly within your browser window.

0.0°

Drag center to move | Click to mark | Scroll to resize