Measuring 22.5° Octagonal & Miter Angles

How to Measure This Angle on an Image or Photo

A 22.5-degree angle is half of a 45-degree miter. When building an 8-sided octagon or framing bay window corners, cutting pieces at 22.5° produces tight 45° corner joints.

Step-by-Step Measurement Procedure

1. Upload your image: Drag and drop a photo or blueprint onto the Online Protractor canvas.
2. Position Point B (Vertex): Drag the central vertex dot directly onto the corner or angle origin.
3. Align Ray A (Baseline): Drag the left handle so ray A aligns perfectly with your reference line.
4. Adjust Ray C (Angle Ray): Drag the right handle until ray C lies exactly along the sloped edge.
5. Read Angle Output: The tool displays degrees, radians, complementary, and supplementary angles in real time.