Snap:
180°
0°
°
Type: Right Angle
Comp: 0°
Supp: 90°
Rad: 1.571
Measure angles from 0° to 360°. Drag to rotate, scroll to adjust, or use arrow keys.
This free online protractor lets you measure and visualize angles from 0° to 360° instantly in your browser. Whether you need to measure acute angles (less than 90°), right angles (90°), obtuse angles (90° to 180°), or reflex angles (180° to 360°), this tool provides precise one-degree accuracy with an intuitive visual interface.
There are multiple ways to set your desired angle: drag the needle around the protractor for quick visual adjustment, use your mouse scroll wheel for fine-tuned control, or type the exact angle value directly into the input field. Quick-access buttons let you jump to common angles like 30°, 45°, 90°, and 180° with a single click. On mobile devices, simply touch and drag the needle to any position.
Enable the Two-Arm Mode to measure angles between any two lines. This feature adds a second green arm that you can position independently. The green shaded area shows the angle between the two arms, making it perfect for measuring angles in diagrams, comparing slopes, or finding the angle between two directions. Simply click near the arm you want to move and drag it to position.
The protractor displays radian values at key angles around the circle, showing the relationship between degrees and radians. You'll see π/6 (30°), π/4 (45°), π/3 (60°), π/2 (90°), and other important radian values that are essential for trigonometry. This makes the tool invaluable for students learning the unit circle and converting between degrees and radians.
Use the snap feature to automatically align to precise angles. Choose from 15°, 30°, or 45° increments to quickly land on commonly used angles. This is especially useful when drawing technical diagrams, setting up equipment at specific angles, or when you need exact measurements without fine-tuning.
The info panel shows comprehensive angle data including: the angle type (Acute, Right, Obtuse, Straight, or Reflex), complementary angle (what adds to 90°), supplementary angle (what adds to 180°), and the radian equivalent. This educational feature helps students understand angle relationships and conversions.
Angles are classified by their measurement: acute angles measure between 0° and 90°, right angles are exactly 90°, obtuse angles fall between 90° and 180°, straight angles are exactly 180°, and reflex angles span from 180° to 360°. The protractor visually highlights the measured angle with a shaded arc for easy understanding.
Lock your angle to prevent accidental changes while referencing it. Use the Copy button to quickly copy the angle value to your clipboard. Enter Fullscreen mode for a distraction-free experience, perfect for presentations or when you need to focus on precise measurements. On mobile devices with accelerometers, you can even use device tilt to measure real-world angles.
Power users can navigate quickly with keyboard shortcuts: Arrow keys adjust the angle by 1° at a time, Home key resets to 0°, End key sets to 360°, and Escape exits fullscreen mode. These shortcuts make the tool efficient for rapid angle adjustments.
Use this digital protractor for geometry homework, calculating roof pitches, setting miter saw angles for woodworking, dividing circles into equal parts, checking inclination angles, learning trigonometry and the unit circle, teaching angle concepts, designing graphics, or any task requiring precise angle measurement. The tool works seamlessly on desktop computers, tablets, and smartphones with full touch support.