Piano / PIA & SING
Practical chord formulas: triads, sevenths and colours
Read degrees against the root’s major scale and separate 7 from maj7.
Practical suggestions for hobbyists, not a guaranteed training programme. Adapt to a comfortable level and stop if you feel pain or tension.
In this article
Formula degrees refer to the major scale on the chord root, not necessarily the song key. For C: 1=C through 7=B; flat lowers a degree by one semitone, and 9 is 2 an octave higher.
C7 differs from Cmaj7. C9 normally includes b7; Cadd9 does not require a seventh. Suspensions replace the third, whereas add9 retains it. Check melody compatibility rather than adding colour everywhere; split notes between hands or invert instead of stretching.
Quick reference
- Major · 1–3–5 → C–E–G
- Minor · 1–♭3–5 → C–E♭–G
- 7 (dominant) · 1–3–5–♭7 → C–E–G–B♭
- Maj7 · 1–3–5–7 → C–E–G–B
- m7 · 1–♭3–5–♭7 → C–E♭–G–B♭
- Sus2 · 1–2–5 → C–D–G (2 replaces 3)
- Sus4 · 1–4–5 → C–F–G (4 replaces 3)
- Add9 · 1–3–5–9 → C–E–G–D (retains 3; no seventh required)
- 6 · 1–3–5–6 → C–E–G–A
- Dim triad · 1–♭3–♭5 → C–E♭–G♭ (not dim7)
Try it step by step
- Locate C major and identify degrees 3 and 7.
- Compare C and Cm by changing only E to Eb.
- Compare C7 and Cmaj7 by changing Bb to B.
- Compare Csus2 and Cadd9: the latter retains E.
- Test one colour with the actual melody before using it.
Check before making it harder
Can you explain Bb in C7 versus B in Cmaj7, and the third in add9 versus sus2? Then transpose.
A song to try this with
Rak · Anchalee JongkadeekijCompare one actual Rak chord with a colour variation against its melody; do not reharmonize automatically.
This is a suggested way to use the song, not a universal difficulty rating or key recommendation.
More in this category
Learn more — Thai-language resources
External learning links open only when selected. No YouTube players or tracking load beforehand.
- สอนเล่น Piano Pop ตอนที่ 4 - การหาคอร์ด 7 / Maj7 / sus2 / sus4 ของมือขวา
BellpianoPop explains 7, maj7, sus2 and sus4 construction.
- คอร์ดแปลกๆ ที่คุณต้องเจอ: sus2 , sus4, 7 , Maj7 , 9 , Maj9 , add9
pllay music design compares suspended, seventh, ninth and add9 sounds.