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Interval Ratios: An Interval Chart Showing Ratios of All Intervals
Table 16 below shows intervals drawn exclusively from the C major scale—no chromatic notes.
TABLE 16 Interval Ratios Occurring Naturally in the Major Scale
| Interval | Semitones | Example | Freq. Ratio | Consonant/Dissonant |
|---|---|---|---|---|
| Minor Second | 1 | B – C | 16 : 15 | Dissonant |
| Major Second | 2 | C – D | 9 : 8 | Dissonant |
| Minor Third | 3 | A – C | 6 : 5 | Consonant |
| Major Third | 4 | C – F | 5 : 4 | Consonant |
| Perfect Fourth | 5 | C – F | 4 : 3 | Consonant |
| Augmented Fourth | 6 | F – B | 45 : 32 | Dissonant |
| Perfect Fifth | 7 | C – G | 3 : 2 | Consonant |
| Minor Sixth | 8 | E – C | 8 : 5 | Consonant |
| Major Sixth | 9 | C – A | 5 : 3 | Consonant |
| Minor Seventh | 10 | D – C | 9 : 5 | Dissonant |
| Major Seventh | 11 | C – B | 15 : 8 | Dissonant |
| Octave | 12 | C – C | 2 : 1 | Consonant |
Of the 12 different intervals, 11 anchor naturally to the tonal centre (the note C) at one end of the scale or the other.
And the only one that doesn’t? It’s that diabolical diabolus in musica, the very devil hisself, the augmented fourth. The one with the weirdest frequency ratio, 45:32.
The same interval can occur in several places in one scale. For example, in the C major scale...
- The minor second (one semitone) occurs in two places: E – F, and B – C.
- The perfect fifth (seven semitones) occurs in four places: C – G, D – A, E – B, and F – C.