180° vs 360°: choosing the right mode
Most confusion comes from this simple fact: 180° mode is for interior angles up to 180°, while 360° mode lets you measure reflex angles (over 180°). If the mode is wrong, the reading can look “flipped” even when your points are correct.
A quick rule you can remember
- If the angle you want is clearly less than a straight line (less than 180°), use 180° mode.
- If you need the outside/reflex angle (greater than 180°), switch to 360° mode first.
- Mode won’t fix alignment. Always align the baseline to a true reference direction before deciding the angle.
How to choose in practice (4 steps)
- Decide what you’re measuring: the inside angle between two sides, or the outside angle around the vertex.
- Align a true baseline (horizontal/vertical) so your reference direction is stable.
- Try 180° mode first for interior angles; if the situation is clearly “over 180°”, switch to 360° mode.
- Sanity-check by looking at the shape: does the number match what your eyes see (small corner vs wide sweep)?
Common mistakes
- Reading an interior angle when you actually need the reflex angle (or vice versa). Decide before you measure.
- Using 180° mode for a reflex angle: the measurement will look inconsistent or capped.
- Letting the baseline drift because the image wasn’t aligned. A stable baseline matters more than snap.
Related
Reflex angles / 360° mode confusion
Fix the common “I can’t measure >180°” scenarios.
Measure a reflex angle (360°)
A step-by-step workflow for angles over 180°.
Alignment checklist
Make the baseline stable before you compare 180° vs 360°.
Measure an angle on a photo
A reliable general workflow that applies to almost any image.