Online Protractor.

Free Online Protractor Tool

Welcome to the online protractor tool at onlineprotractorapp.com. Measure angles digitally without a physical protractor. Upload any image, place three measurement points, and get the precise angle in degrees. Perfect for students, engineers, architects, and DIY projects.

Our online protractor tool works entirely in your browser. No software to install, no accounts needed. The protractor updates in real time as you move the measurement points. Each measurement shows the angle type (acute, right, obtuse, straight, or reflex), plus the complementary and supplementary angles.

Whether you are checking angles on a technical drawing, solving geometry homework, measuring roof pitches, or verifying furniture cuts, this free digital protractor gives you the accuracy you need. Download your measurements as a PNG to include in reports or share with colleagues.

How to Measure an Angle Online

1. Upload an image using the button above, or start with the default protractor.
2. Drag the black crosshair hub to move the protractor's center onto the vertex you want to measure.
3. Drag the red dots at either end of the flat edge to rotate or resize the protractor to fit your image.
4. Click anywhere on the canvas to drop a ray; click again elsewhere to drop another. Each pair of neighboring rays gets a labeled angle.
5. Drag any ray's endpoint at any time to fine-tune it. The angle updates instantly and is listed below the canvas.

What is a Protractor?

A protractor is a measuring instrument used to measure angles. A standard protractor measures 0 to 180 degrees. Our digital online protractor lets you measure any angle on any image. Unlike physical protractors, you can zoom in for pixel-level precision and export the result.