An interval measures the distance between two notes.
We will first discuss generic intervals, which are measured on the staff.
When two notes occupy the same line or space, they are a first (or a prime) apart.
C to C is an example of a first.
D to D and E to E are also firsts.
Accidentals are ignored when measuring generic intervals, only staff position matters.
C – C#, D – Db, and A# – Ab are still firsts.
As the notes become further apart on the staff, the interval type increases.
C – D, D – E, and E – F are all seconds.
C – E, D – F, and E – G are all thirds.
Notice that thirds will always share the same staff position type — either both on a line or both on a space.
C – F, D – G, and E – A are all fourths.
C – G, D – A, and E – B are all fifths.
C – A, D – B, and E – C are all sixths.
C – B, D – C, and E – D are all sevenths.
C – C, D – D, and E – E are all eighths.
Use this chart to reference generic intervals.