How long does a smart radon detector take to give an accurate reading?

Most consumer radon monitors in this group advertise a usable short-term reading within about a week, with accuracy improving over longer continuous monitoring. The EPA generally recommends acting on results from longer-term measurement, and several of these devices (RadonEye, Airthings, X-Sense) market 'continuous' long-term tracking precisely so you can watch trends rather than rely on a single short test.