Here is a fretboard diagram of all the notes on the guitar. Play the notes on each string from the open notes to the 12th fret. The note on the 12th fret is one octave higher than the open note, e.g., the open 6th string is an E note and the note on the 12th fret of the 6th string is also an E note, but is one octave higher.
# indicates a sharp, which raises the note by one semitone (1 fret).
b indicates a flat, which lowers the note by one semitone (1 fret).
@ indicates a natural, which cancels out the effect of a sharp or flat.
One more useful way of learning the notes is to go across each fret. Once again, use sharps as you go higher in pitch and flats as you go back down.
The notes E F and B C are always one semitone apart (one fret). All other notes are a tone apart (2 frets). Sharps (#) and flats (b) are found between the notes that are a tone apart.
This scale is called the chromatic scale and contains all the #’s and b’s possible. C sharp (C#) has the same position on the fretboard as D flat (Db). They are the same note but can have different names depending upon what key you are playing in. The same applies to D#/Eb, F#/Gb, G#/Ab, A#/Bb. These are called enharmonic notes. The Bass Fretboard diagram includes all of these sharps and flats.
Also notice that:
These note positions are important to remember because they are the basis for tuning your bass to itself.