How are whole notes, half notes, quarter notes, and eighth notes related in duration?

In Western music notation, the duration of notes is defined by their relationship to one another, with each symbol representing half the duration of the note that precedes it.1

The hierarchical relationship between these common note values is as follows:

• Whole note: The longest of these four values, serving as the base unit in this sequence.21
• Half note: Equal to one-half of a whole note.21
• Quarter note: Equal to one-half of a half note, or one-quarter of a whole note.21
• Eighth note: Equal to one-half of a quarter note, or one-eighth of a whole note.21

These symbols do not indicate absolute time but rather provide the duration of a note relative to the other notes in a piece. Their specific rhythmic value is ultimately determined by the time signature established for the music.12