Clarinets are transposing instruments. Notation is in treble clef.
Notation for the bass clarinet is written in treble and bass clef.
All clarinets have the same fingering. The written pitches refer to the fingering that the clarinetist is to use on his or her instrument. In other words, if a particular written pitch is to be played by two clarinets in different tunings, both instruments use the same fingering. Because the fundamental pitch of each instrument is different, the same fingering produces a different sounded pitch.
This practice is a historical development and has the advantage for the musician of his having to learn only one system of fingering, which he uses on every instrument in the clarinet family. Thus the fingering of a notated Bb major scale is always the same, but played on a Bb clarinet it sounds as an Ab major scale, and on an A clarinet as a G major scale.
Clarinetists read the score as if it were written for a C clarinet and transpose according to which instrument they are playing. On the C clarinet the sound is as written.
This correlation between notation and sound means that the written compass of all clarinets ranges from E3 to C7.
Higher-pitched clarinets sound higher than written. The Eb clarinet sounds a minor third higher than written, the D clarinet a major second:
Lower-pitched clarinets sound lower than written. The Bb clarinet sounds a major second lower than written, the A clarinet a minor third. The basset horn in F sounds a fifth lower than written, the bass clarinet in Bb a ninth lower: