Octave clef
An octave clef is a clef with a small number below or above it that shows an octave of displacement. A common form is the treble clef with an 8 below: the notes sound an octave lower than they are written.
- Sign
- treble clef with a small 8 below
- Effect
- sounds an octave lower than written
- Used for
- tenor voices, guitar
- 8 above / 15
- one octave higher / two octaves
An octave in the clef
The number at the clef does not change the position of the lines but the meaning of the notes. A small 8 under the treble clef says: everything in this staff is played or sung an octave lower than the notes show. In this way low voices can be notated in the comfortable range of the treble clef, saving ledger lines below the staff. With an 8 above, the sound shifts an octave upward, with a 15 by two octaves.
Treble clef with 8 below (input: sounding notes)
The notes sit an octave higher in the staff than they sound: the sounding C4 is written as C5. The 8 under the clef is a reminder of this.
The same sounding notes in the ordinary treble clef
In the ordinary treble clef the sounding C4 lies on the first ledger line below the staff. The octave clef avoids these ledger lines.
The signs
The table shows the usual signs at the clef and their effect.
| Sign at the clef | Effect on the notes |
|---|---|
| 8 below the clef | sounds an octave lower than written |
| 8 above the clef | sounds an octave higher than written |
| 15 below or above the clef | displacement by two octaves |
Who needs it
The treble clef that transposes downward is above all the clef of the tenor voice: the male voice sings an octave lower than is written in the treble clef. Guitar music, too, is actually written in this clef, only the 8 is usually left out there. That the 8 is often missing does not change the meaning: the context, that is instrument and voice range, shows how to read.
Confusion with the tenor clef
In choral scores this clef is also called the “tenor clef”. But it is not the C clef on the fourth line, which is called that in other contexts. When you read “tenor clef”, the context decides: a choral score usually means the treble clef with 8, orchestral music for cello, bassoon and trombone the C clef.
Common mistakes
- Overlooking the 8: Then you play or sing an octave too high.
- Confusing the octave clef with the tenor clef: The name is used twice.
- Applying the 8 only to notes in the staff: It also holds for notes on ledger lines.
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Related terms
Treble clefClefTenor clefOttavaOctaveGuitarOne-line octave
Editor: Maik Krohm · reviewed on 3 October 2026
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