Perfect fifth, 3 1/2 whole steps or 7 half steps:
Augmented fifth, 4 whole steps or 8 half steps:
Diminished fifth, 3 whole steps or 6 half steps:
When analyzing the quality of a fifth we should know that:
If there are accidentals you should identify the interval without accidentals and then analyze the effect of the accidentals.
Another example: G-Db:
Identifying fifths by counting whole and half steps is slow and confusing.
See I > Intervals for related entries. To learn about go to Tutorials > Intervals.