treble clef: which line does the curl mark?
A treble clef is a G clef whose curl wraps the second line, so that line is G4. From the bottom, the five lines read E4, G4, B4, D5, F5. Recomputed with A4 = 440 Hz, G4 is 392.00 Hz. On 21 October 2026 this site’s key finder read a 24-second violin adagio written in this clef as G minor, Camelot 6A, at 70%.
What the curl fixes
Wikipedia’s Clef article, read on 21 October 2026, says the G clef fixes the G above middle C on the line that passes through the curl. In the treble clef that line is the second line from the bottom, and the note is G4. Middle C is C4. A fifth above C4 is G4, which is why the curl and the second line name the same pitch.
Step down from that line and middle C lands on a ledger line under the staff. Second line G4, space below it F4, bottom line E4, space under the staff D4, then one ledger line: C4. The same article’s drawing of middle C on the treble staff puts it there. C4 recomputes to 261.63 Hz.
The same article lists violin, flute, oboe, clarinet, saxophone, trumpet, and guitar among the instruments that read a treble clef. It is also the upper staff of the piano grand staff. In the octave-clef section the article says that, starting in the 18th century, music for some instruments such as the guitar, and for the tenor voice, has used the treble clef although those parts sound an octave lower. A written G4 on guitar is the pitch an octave under the G4 this page calculates. Violin and flute sound the written pitch. The clip below is violin.
The five lines and four spaces
The same Clef article, still the 21 October 2026 reading, prints two sayings for this clef. Lines, bottom to top: “Every Good Boy Does Fine”, E G B D F. Spaces, bottom to top: “F A C E”. Those four words and that sentence are the article’s mnemonics, not a second source.
| Line | Pitch | Hz | Saying |
|---|---|---|---|
| Bottom | E4 | 329.63 | Every |
| 2nd | G4 | 392.00 | Good |
| 3rd | B4 | 493.88 | Boy |
| 4th | D5 | 587.33 | Does |
| Top | F5 | 698.46 | Fine |
| Space | Pitch | Hz | Letter |
|---|---|---|---|
| 1st | F4 | 349.23 | F |
| 2nd | A4 | 440.00 | A |
| 3rd | C5 | 523.25 | C |
| 4th | E5 | 659.26 | E |
Numbers you can check
Equal temperament, A4 = 440 Hz, sets a pitch at 440 × 2((midi − 69) ÷ 12) Hz. The five lines, bottom to top:
E4 is midi 64: 440 × 2((64 − 69) ÷ 12) = 440 × 2(−5 ÷ 12) = 329.627… Hz, which rounds to 329.63 Hz.
G4 is midi 67: 440 × 2((67 − 69) ÷ 12) = 440 × 2(−2 ÷ 12) = 391.995… Hz, which rounds to 392.00 Hz. That is the line inside the curl, and it is also the tonic of the G minor reading below.
B4 is midi 71: 440 × 2((71 − 69) ÷ 12) = 440 × 2(2 ÷ 12) = 493.883… Hz, which rounds to 493.88 Hz.
D5 is midi 74: 440 × 2((74 − 69) ÷ 12) = 440 × 2(5 ÷ 12) = 587.329… Hz, which rounds to 587.33 Hz.
F5 is midi 77: 440 × 2((77 − 69) ÷ 12) = 440 × 2(8 ÷ 12) = 698.456… Hz, which rounds to 698.46 Hz.
C4, the ledger line under this staff, is midi 60: 440 × 2((60 − 69) ÷ 12) = 440 × 2(−9 ÷ 12) = 261.625… Hz, which rounds to 261.63 Hz. Those figures are arithmetic. The recording below is a separate reading. On 21 October 2026 this site’s key finder called the opening of Bach’s G minor violin adagio G minor at 70% confidence.
A recorded example you can check
Wikipedia’s article Sonatas and Partitas for Solo Violin, read on 21 October 2026, heads a section “Sonata No. 1 in G minor, BWV 1001” and lists Adagio as the first movement. The same article says the key signature of the manuscript suggests D minor, and that this was a notational convention in the Baroque period rather than a claim that the piece is Dorian. The autograph page itself, Commons file BWV1001 adagio autograph manuscript 1720.jpeg, is headed “Sonata 1.ma a Violino Solo senza Basso” and “Adagio”, and each staff opens with a treble clef and one flat. The work list names G minor. The ink shows a violin staff, a treble clef, and one flat. The two pages do not copy each other: one is a work list, the other is the manuscript.
On 21 October 2026 at 10:40 EDT this site’s key finder read this 24-second clip as G minor, Camelot 6A, at 70% confidence, with the hint “Check against your audio”. It listed C minor (Camelot 5A, 21%) and B flat major (Camelot 6B, 2%) next. The screen did not add a low-confidence note. That percentage is the finder’s estimate for this file, not a measured accuracy rate. The work list names the sonata G minor, and the finder named G minor as well.
What our key tools tell you
Give a recording to the key finder for the key it hears. The clef is read from the staff, not from that percentage. A treble clef still marks G4 on the second line when a short clip comes back at some other name. Printed sharps and flats that sit after the clef are a different question, answered on the key signature chart.
treble clef: quick answers
Which line does a treble clef mark?
The second line from the bottom. The curl wraps that line, and the note is G4, 392.00 Hz.
What are the five lines?
Bottom to top: E4, G4, B4, D5, F5. The saying in the Clef article is “Every Good Boy Does Fine”.
What are the four spaces?
Bottom to top: F4, A4, C5, E5. The same article spells them F A C E.
Where is middle C?
One ledger line below the staff. That note is C4, 261.63 Hz.
What did the finder return for the violin adagio?
G minor, Camelot 6A, 70% confidence. C minor at 21% and B flat major at 2% were the next two candidates.
What this page leaves open
- This page is only the treble clef. The bass clef, whose two dots pinch F3, is a different staff.
- 392.00 Hz and the other hertz figures are equal-temperament arithmetic from A4 = 440 Hz. They were not measured off the violin recording.
- The 70% figure is this 24-second file only. It is not an accuracy rate for every piece written in a treble clef.
- The autograph prints one flat after the treble clef. The work list still names the sonata G minor, and this page does not redraw that signature as two flats.