Begin with the siren above: slide quietly from a comfortable low note to a comfortable high one and back, on "ng" or "oo". Keep it easy, and notice three places: where the bottom stops being clear, where the top stops being easy, and where in between the sound changes gear. Those three points are most of what this guide explains. HOW NOTES ARE NAMED. Singers name notes with a letter and a number, like C4 or A3. The letter is the note and the number is the octave. Middle C on a piano is C4, the C an octave below is C3, and the number goes up at every C, so B3 sits just below C4. When a chart says a baritone sings from A2 to A4, it means from the A just below C3 up to the A just above middle C: two octaves. RANGE AND COMFORTABLE RANGE. Your full range is everything from the lowest to the highest note you can produce. Your comfortable range is narrower: the notes you can sing words on, at a moderate volume, again and again, without strain. Songs live in the second kind. A note you reach once at the end of a siren does not make a song that sits there comfortable. WHERE A SONG SITS. Songs have a range too, and the more useful number is where the melody spends its time, which singers call the tessitura. Published sheet music for "Someone You Loved" by Lewis Capaldi puts the melody between Eb3 and Bb4, and by our estimate it spends most of its time between D4 and A4. A singer whose comfortable top is around A4 may reach the Bb4 and still find the song tiring, because the chorus keeps returning to their ceiling. When you choose songs, compare where they sit with where you are comfortable, not just the top notes. VOICE TYPES ARE LABELS FOR SPANS. Bass, baritone, tenor, alto, mezzo-soprano and soprano are names for conventional spans, and they overlap a lot. The textbook spans we use are roughly E2 to E4 for bass, A2 to A4 for baritone, C3 to C5 for tenor, F3 to F5 for alto, A3 to A5 for mezzo-soprano and C4 to C6 for soprano. Real voices cross those lines all the time. Teachers place a voice using its comfortable range, where it changes gear and how it sounds, over time and across songs; two endpoints cannot settle it on their own. WHY YOUR RANGE CHANGES FROM DAY TO DAY. The same voice measures differently cold and warmed up, morning and evening, rested and after a long day of talking, and a little differently on different microphones and in different rooms. A single measurement is a snapshot. To compare, measure under the same conditions each time: a rested day, after a warm-up, in the same spot. WHAT PRACTICE CHANGES. Regular practice usually widens the comfortable range more than the extremes: notes near the edges get easier and steadier, the gear change gets smoother, and songs that were tiring become singable. How much, and how quickly, varies from voice to voice, and nobody can promise you a number of notes. Diagnostic question: after the siren, sing a short phrase you know near the top of your comfortable range, then the same phrase two semitones lower. Which version could you sing ten times in a row? That answer tells you more about your usable range than the highest note you can touch. MEASURING YOURS. The free range finder records the lowest and highest notes you can repeat in one session. It does not measure your comfortable range, your gear change or your tone, and it does not assign a voice type. Use it alongside the siren and the comfortable-key check above. If reaching for the edges hurts or leaves you hoarse, stop: no measurement is worth pain, and pain or hoarseness that lasts is a reason to see a doctor.