Fourths can be perfect, augmented or diminished. Below you can see that the number of steps determines the quality of the interval:

Perfect fourth, 2 1/2 whole steps or 5 half steps:

perfect fourth

Augmented fourth, 3 whole steps or 6 half steps:

augmented fourth

Diminished fourth, 2 whole steps or 4 half steps:

diminished fourth

Identifying fourths

When analyzing the quality of a fourth we should know that:

If there are accidentals you should identify the interval without accidentals and then analyze the effect of the accidentals.

Example: G-C#:

Another example: C#-F#:

Identifying fourths by counting whole and half steps is slow and confusing.

See I > Intervals for related entries. To learn about go to Tutorials > Intervals.


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José Rodríguez Alvira.