Angle type
Right Angle — Exactly 90°
A right angle measures exactly 90° — one quarter of a full circle (π/2 radians). It’s the familiar square corner you see on paper, screens, and walls.
Updated Online Protractor
Measure: 90° exactly · π/2 ≈ 1.5708 rad.
Where you see it: book corners, phone screens, window frames, the “L” shape.
In the tool, a right angle gets a special green highlight and the pill reads Right.
Tip: set snap to 90° or 15° to land exactly on 90°.
How to confirm a right angle
- Place the center on the vertex and align handle A with one edge.
- Drag handle B — when the reading snaps to
90.0°the tool labels it Right. - If you see 89.7° or 90.4°, nudge with arrow keys (1° steps, Shift 5°) or disable snap for sub-degree fine-tuning.
Measure from a photo? Corners can look off due to perspective — photograph straight on, centered, with the lens parallel to the surface. Image tips →