About Free Online Protractor
Empowering engineers, architects, students, and DIY builders with client-side, high-precision geometry tools.
Smart Features for Engineering, Math & Construction
100% Client-Side Privacy
All image rendering, angle calculations, and pixel operations happen strictly inside your web browser. No images are ever uploaded to cloud servers.
Sub-Pixel Math Engine
High-precision 64-bit floating point vector math paired with a 4x Loupe scope magnifier ensures accuracy down to 0.01 degrees.
Multi-Unit Real-Time Solver
Instantly translates any angle into Degrees, Radians, Gradians, Slope Grade %, and Roof Pitch rise-to-run ratios.
Free Online Protractor
Architects & Civil Engineers
Verify roof slope pitches, wall corner squareness, and structural angles directly on CAD PDF blueprint exports.
Carpenters & Woodworkers
Calculate rise-to-run framing ratios (e.g. 6:12 pitch) and stair stringer angles in seconds.
Math Teachers & Students
Visualize geometric angles (acute, right, obtuse, reflex), radians, and trigonometrical triangle properties.
Medical & Orthopedic Analysts
Analyze Cobb angles and joint range-of-motion on X-ray photos with complete patient privacy.
Modern Web Architecture
High performance client-side rendering.