Chord Decoder
Every major chord is the same 3 numbers.
No theory needed. Tap a chord, see its numbers, move it to any key.
C major
Numbers0 · 4 · 7
Notes: C · E · G
Same numbers, new key. That’s the whole trick.
Move it to another key
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In short
Piano chords follow number recipes. Count the 12 notes from 0 to 11, and every major chord is 0-4-7 above its root, every minor chord 0-3-7. Learn one recipe and you can build that chord in all 12 keys.
How it works
- Tap a chord on the keyboard.
- See the 3 numbers that build it.
- Switch keys and watch the numbers stay the same.
Questions
Do I need to read music?
No. You only need to count keys.
Why 0 to 11 and not 1 to 12?
0 to 11 is the standard in theory books and music software. Some players count from 1, which works too.
Is this the Nashville number system?
No. That numbers chords by their place in a key. This counts the 12 notes, and it works in every key.
What’s in the cheat sheet?
The note map and the chord recipes on one printable page.
What happens to my email?
You get the cheat sheet and a short 3-email "Play Your First Song Tonight" series. Unsubscribe anytime.