Angle Types
Updated Online Protractor
Understanding the classification helps you read the result chip correctly. The tool shows “Acute”, “Right”, “Obtuse”, “Straight”, or “Reflex” next to the live value. Prefer the dedicated pages: Acute · Right · Obtuse · Straight · Reflex.
Acute angle — 0° < angle < 90°
Example 30°, 45°, 60°. Common in triangles and corners. Drag the second ray just a little from the baseline. Dedicated acute guide →
Right angle — 90°
Exactly 90°. The tool highlights this specially. Use Snap 15° or 90° to land precisely. Right angle guide →
Obtuse angle — 90° < angle < 180°
Example 120°, 135°. Wider than a right angle, less than a straight line. Obtuse guide →
Straight angle — 180°
A straight line. In 180° mode the protractor shows this as the flat edge. Straight guide →
Reflex angle — 180° < angle < 360°
The larger reflex. Toggle “Measure reflex angle” in the toolbar to swap inner/outer. Example 270°. Reflex guide →