Range is the set of pitches available under stated conditions. A useful working range is made of notes you can repeat in phrases without pain, hoarseness, unusual fatigue, or strain, not one extreme sound produced once.
Measure on a rested day at an easy volume. Begin near speaking pitch and move outward gradually. Save the microphone, room, warmup, and key with the endpoints so a later comparison means something.
Work middle-out with gentle patterns such as humming, lip trills, or straw phonation if those feel easy for you. One semi-occluded exercise is not universally safer or guaranteed to add notes.
Register labels describe coordination choices and are used differently across teachers and styles. A break or gear change does not reveal one cause from sound or sensation alone.
Transpose repertoire when the original key puts repeated phrases at the edge. Changing key is a musical decision, not a failed range-extension program.
Do not test the maximum every day or attach a deadline to a semitone. Compare several rested sessions and prioritize the quality and repeatability of phrases over the endpoints.
Sudden or persistent range loss, pain, or hoarseness belongs with a qualified health-care provider or voice professional. A range app can record pitches; it cannot determine the cause of a change.