1
Measuring Angles from an Image or Screenshot
1. Take a screenshot or download the photo/diagram you want to measure.
2. Click the Image button on the toolbar or simply drag and drop the file directly onto the canvas.
3. Adjust the Image Opacity slider (e.g. to 80%) so you can see both the image details and protractor tick marks clearly.
4. Drag the protractor center to the vertex of the angle.
5. Use the circular rotation handle (top) to align the 0° baseline with the bottom arm, then drag the second ray to the top arm.
6. The exact angle is displayed in real-time in the center arc badge.
2
Using the 3-Point Angle Tool (Vertex + 2 Arms)
When measuring triangles or shapes without moving a circular dial:
1. Select the 3-Point Angle tool from the top toolbar (Shortcut: 'P' or '3').
2. Click once to place the Vertex point.
3. Click a second time to place Point A (First arm).
4. Click a third time to place Point B (Second arm).
5. The angle between the two lines is calculated instantly with an arc badge and added to your measurement export list.
3
Live Camera Measuring for Carpentry & Physical Objects
1. Open realonlineprotractor.com/app on your smartphone or tablet.
2. Click the Camera button and grant browser webcam permissions.
3. Point your camera perpendicularly at the physical joint, miter cut, roof pitch, or staircase.
4. Align the on-screen protractor rays with the physical edges visible on your screen.
5. Click Export > PDF Report to save a dated measurement document with photo proof.