I'm in key X and want to go to key Y: How can I do that?

1. Pick one of the modulations to the target key from the list (or choose a chord from the list of key-defining chords).

2. If it doesn't sound right:
a) Pay attention to voice leading — follow the usual rules (e.g., resolving suspensions, avoiding unnecessary large leaps, etc.).
b) Add extra tones from the target key.
c) Use a chord with fewer notes — one that can also includes the target key as end key. (Use the numbers listed under "Containing" on a modulation's detail page as links to these modulations, or just browse the list.)
d) Build an indirect modulation by chaining multiple modulations through intermediate keys.
e) Go back to step 1 and try a different modulation.

Learn more about the theory behind this

Which number is which tone?

0: C
1: C#/D♭
2: D
3: D#/E♭
4: E
5: F
6: F#/G♭
7: G
8: G#/A♭
9: A
10: A#/B♭
11: B

Key-Defining Chords

A key-defining chord is a chord that can only appear in one key. That means that playing this chord will always lead you to this key, regardless of in which keyset you were before.

The following pitch-class sets are the key-defining chords for C major and C minor:

Major (2 chords):
[4, 5, 7, 11]
[5, 7, 10, 11]

Minor (8 chords):
[2, 3, 7, 11]
[0, 3, 8, 11]
[3, 5, 7, 11]
[0, 2, 3, 11]
[5, 7, 8, 11]
[0, 7, 8, 11]
[2, 7, 8, 11]
[0, 3, 5, 11]