Radar detector alert distance can vary due to many different factors.
In ideal situations you can get over 10 miles of range.
Here in Seattle, my maximum alert distance is no more than a mile due to the terrain and trees.
In tougher situations you may get 1/4 of a mile or less.
Lower end detectors work fine in easy situations, but may not give any advanced warning in challenging situations. Tougher situations require more sensitive radar detectors.
Maximum alert distance can be affected by many factors including:
- Radar detector sensitivity
- Which settings you’re running on your detector
- Radar gun output power
- What direction the officer has his gun pointed
- Terrain (Radar can travel farther in flat terrain and is blocked by hills, curves, and trees)
- Instant on usage
- On-axis vs. off-axis sensitivity
For more info, see this video: