Protractor - Measure Angles in Images
Measure angles in images online. Click three points to measure angles precisely for geometry, construction, and design work.
or drop image here or paste
Measure angles in images online. Click three points to measure angles precisely for geometry, construction, and design work.
or drop image here or paste
The Protractor Tool allows you to measure angles in any image with precision. Click three points on your image - the vertex (center point) and two points on each arm - to instantly calculate the angle in degrees. Perfect for geometry homework, construction plans, engineering drawings, architectural blueprints, and design work where accurate angle measurement is essential.
Upload your image containing the angle you want to measure. First, click on the vertex point (the corner where the two lines meet). Then click on a point along the first arm of the angle, and finally click on a point along the second arm. The tool automatically calculates and displays the angle in degrees. Adjust line width and color for better visibility, then download your annotated image showing the measured angle with labeled points (V for vertex, 1 and 2 for the arms).
Use the protractor tool for geometry problems to verify angle calculations, construction projects to measure roof pitches and corner angles, architectural plans to check design specifications, woodworking projects to measure cut angles, engineering drawings to verify technical specifications, or design work to measure perspective angles. The tool works with photographs of physical objects, scanned drawings, digital blueprints, CAD exports, and any image format including JPG, PNG, and WebP.
The protractor calculates angles using the arctangent function (Math.atan2) which provides precise mathematical measurements based on the coordinates you click. Unlike physical protractors that can be difficult to align, the digital protractor lets you zoom in and click exact points for highly accurate measurements. The angle is calculated as the difference between the two arms relative to the vertex point, giving you the interior angle formed by the three points.
Measure multiple angles in the same image by clearing points and selecting new ones. Customize the appearance with adjustable line width (1-10 pixels) and choose any color for the angle lines to match your preference or stand out against your image background. Download your annotated image in PNG format for lossless quality with transparency support, JPG for smaller file sizes, or WebP for optimal compression. The downloaded image includes the drawn angle lines, labeled points, and maintains your original image quality.