Online Protractor
Drag the arm to measure any angle. Enable a second arm to measure between two lines. Switch between 180° and 360° mode.
Drag the yellow arm to measure an angle · Drag the center circle to reposition
Common Angles
Frequently Asked Questions
How do I use this online protractor?
Drag the yellow arm from the center to measure an angle against the baseline. Enable a second arm to measure angles between two lines. The angle updates live as you drag.
Can I measure angles between two lines?
Yes. Click "Two Arms" to enable a second arm. Drag each arm to one of the lines you want to measure. The calculator shows both individual angles and the angle between the two arms.
What is a protractor used for?
A protractor measures angles in degrees. It's used in geometry, drafting, woodworking, construction, and navigation. A standard protractor measures 0–180°. A full-circle protractor (360°) is also called a "bevel gauge."
How do I measure a 45 degree angle?
Drag the arm until the readout shows 45°. With snap enabled (1° or 5°), it will lock precisely at 45°. A 45° angle is halfway between 0° and 90°, pointing diagonally up-right from the baseline.
What is a 180 degree angle?
A 180° angle is a straight line — both ends point in opposite directions along the same baseline. On this protractor, 180° is the leftmost point of the arc.
How do I measure an obtuse angle?
An obtuse angle is any angle greater than 90° and less than 180°. Drag the arm past the 90° mark. The arm will point to the upper-left quadrant of the protractor.