How to measure reflex angles (360°) correctly
You need an angle over 180°, but 180° mode doesn’t make sense, or you’re unsure which scale to read.
Why this happens
- You’re measuring a reflex angle (>180°) while the protractor is in 180° mode.
- You’re reading the interior angle when you intended the outside angle (or vice versa).
- The baseline isn’t aligned to a clear edge, so the reference direction is drifting.
How to fix it
- Switch to 360° mode before reading angles larger than 180°.
- Decide which angle you want: interior (<180°) or reflex (>180°) around the vertex.
- Re-align the baseline using the grid/guides so one side is a stable reference.
- If you still get inconsistent values, re-check image alignment and place the center exactly on the vertex.
Related
Angle types (including reflex)
A quick reference for recognizing reflex angles and choosing the right mode.
Virtual vs digital protractor basics
How 180° vs 360° mode maps to real measuring needs.
Alignment checklist
Reduce system errors by fixing tilt and perspective first.
Angle looks inaccurate
If the reading looks wrong, check vertex placement and mode.