Once you know the interval, you can figure the octave by adding the interval to the root. For example, if the root is C and the interval is 3, the octave is E. If the root is C and the interval is 5, the octave is G.
Here is a table of octaves for the 12 major and minor keys:
| Key | Root | Interval | Octave |
|---|---|---|---|
| C major | C | 8 | C |
| C minor | C | 7 | B |
| D♭ major | D♭ | 8 | D♭ |
| D♭ minor | D♭ | 7 | C♭ |
| D major | D | 8 | D |
| D minor | D | 7 | C |
| E♭ major | E♭ | 8 | E♭ |
| E♭ minor | E♭ | 7 | D♭ |
| E major | E | 8 | E |
| E minor | E | 7 | D |
| F major | F | 8 | F |
| F minor | F | 7 | E |
| F♯ major | F♯ | 8 | F♯ |
| F♯ minor | F♯ | 7 | E♯ |
| G major | G | 8 | G |
| G minor | G | 7 | F♯ |
| A♭ major | A♭ | 8 | A♭ |
| A♭ minor | A♭ | 7 | G♭ |
| A major | A | 8 | A |
| A minor | A | 7 | G |
| B♭ major | B♭ | 8 | B♭ |
| B♭ minor | B♭ | 7 | A♭ |
| B major | B | 8 | B |
| B minor | B | 7 | A |
Here are some tips for figuring octaves:
* If the interval is greater than 7, subtract 7 from the interval and then add the result to the root. For example, if the root is C and the interval is 9, the octave is A.
* If the interval is less than 1, add 7 to the interval and then add the result to the root. For example, if the root is C and the interval is 0, the octave is C.
* For diminished chords, the octave is the same as the root.
* For augmented chords, the octave is the same as the root plus 1.
Figuring octaves is an important skill for musicians who want to understand and create music. By following these tips, you can easily figure octaves for any chord.