How to Measure Angles Online.
Follow this simple guide to measure any angle from images, camera feeds, or virtual protractor overlays.
Select Your Input Source (Photo, Camera, or Canvas)
Click Upload Image to load any image file (PNG, JPG, WEBP, SVG) from your phone or computer. Alternatively, click Use Camera to open your device webcam and measure physical objects directly in front of your camera.
Switch Between 180° Semicircle & 360° Full Circle Modes
• 180° Half Protractor: Perfect for standard triangle geometry, flat straight lines, and acute/obtuse angles up to 180°.
• 360° Full Circle Protractor: Click the ◯ 360° Full toggle to measure reflex angles (180°–360°), circular gears, compass bearings, and 4-quadrant polar trigonometry.
Click the Arc to Pin Multi-Ray Angles Across All Quadrants
Click anywhere on the protractor arc to place numbered ray pins (1, 2, 3, etc.). freeProtractor automatically draws colored angle sectors between adjacent rays with floating degree badges and calculates span angles between custom selected pairs.
Read Instant Reflex Angles, Bearings & Dual Concentric Scales
The dashboard displays live angle degrees, radians, gradians, and quadrant badges (Q I, Q II, Q III, Q IV). Read clockwise bearings from the outer scale or counter-clockwise reflex supplements from the inner scale.
Save, Log Multiple Angles, & Export Reports
Click Save Angle to record multiple angles into your measurement log. Export high-resolution annotated PNG images or download comprehensive CSV reports containing exact degrees, radians, and trigonometric classifications.
Ready to Measure Your First Angle?
Open freeProtractor now — 100% free, no login required.
Launch freeProtractor Studio➔