在乐理中, 五度圈 (或者 四度圈/四度圈) 显示了音阶中十二个音之间的关系，它们相应的调号和相关联的大小调式。

•  在一个八度内顺时针演奏五度圈

•  在一个八度内逆时针演奏五度圈

In music theory, the circle of fifths (or circle of fourths) is a visual representation of the relationships among the 12 tones of the chromatic scale, their corresponding key signatures, and the associated major and minor keys. More specifically, it is a geometrical representation of relationships among the 12 pitch classes of the chromatic scale in pitch class space. In musical pieces from the Baroque music era and the Classical era of music and in Western popular music, traditional music and folk music, when pieces or songs modulate to a new key, these modulations are often associated with the circle of fifths.