Alto clef
The alto clef is the C clef on the middle line. It fixes middle C (C4) exactly in the middle of the staff. It is the clef of the viola, whose range lies exactly where neither treble nor bass clef would manage without many ledger lines.
- Fixed
- C4 on the third (middle) line
- For
- viola
- Family
- C clef
- Italian
- chiave di contralto
The viola's clef
The symbol library describes the alto clef as a C clef on the third line that marks middle C in the middle of the staff. It is used mainly for the viola, because its range lies exactly where neither treble nor bass clef would manage without many ledger lines. The page Reading music mentions it as the viola clef among the C clefs, which only become important for advanced players.
| Position | Note in the alto clef |
|---|---|
| space above | D4 |
| middle line | C4 |
| space below | B3 |
How to read it
You need only one anchor note: the middle line is C4. From there you count line by line. Middle C is the same note as in the treble and bass clefs, only here it sits in the middle, whereas in the treble clef it lies on the first ledger line below and in the bass clef on the first above.
Viola
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Eine kleine Nachtmusik, Stimme Viola Wolfgang Amadeus Mozart, K. 525, 1st movement Allegro, Serenade in G major · viola · 2 pages
The viola part begins in 4/4 time with one sharp and the dynamic marking f. The clef sign sits on the middle line.
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Related terms
C clefClefTenor clefTreble clefBass clefOne-line octave
Editor: Maik Krohm · reviewed on 3 October 2026
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