2 Techniques to Harmonize Any Melody on Piano (Chord Trees and Cadences)

You can harmonize almost any melody on piano either by building chord trees on its long, strong-beat notes, or by ignoring the melody and trying common cadences and progressions like V–I, IV–I, ii–V–I and I–V–vi–IV until your ear picks the best fit.

Video lesson by Jason Zac · Intermediate · 29 min

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This lesson from Jason Zac at Nathaniel School of Music gives you two survival strategies for finding chords to a melody you have never prepared. That might be a singer at a gig, a band jam or a studio session. It suits pianists who know their major scales and basic triads and want to accompany confidently on the fly. The example melody is in F major (one flat).

Know your diatonic chords first

Both methods depend on knowing the chords available in the key. In F major they are:

• I: F major (F A C)
• ii: G minor (G Bb D)
• iii: A minor (A C E)
• IV: Bb major (Bb D F)
• V: C major (C E G)
• vi: D minor (D F A)
• vii: E diminished (E G Bb)

Method 1: Chord trees (guided by the melody)

Step 1: Find the landing tones

Play the tune and notice which notes are long and fall on the first beat of a bar. These are landing tones on strong beats, and they are the ones to harmonize. Short notes that fall between beats, such as the Bb and F in this melody, are passing tones. You can leave them unharmonized.

Step 2: Grow the branches

For each landing note, list every chord in the key that contains it. Those options are the branches of the chord tree.

• C appears in F major, A minor and C major. An A minor chord with the Bb passing note gives a dark, Phrygian flavour, because Bb is a flat second above A.
• If the phrase moves from C to A, choose a chord that suits both notes. A minor and F major each contain C and A. Going beyond triads, D minor 7 (D F A C) holds both as well.
• E fits A minor or C major. If you used one of them earlier, the other gives some variety.

Step 3: Let your ear choose

Theory gives you many options for each melodic unit, and your ear makes the final call. One version from the lesson runs A minor – D minor – Csus4 – C – F. Here Csus4 resolving to C sets up the tonic. A quick F to C gospel-style movement also works. C to F alone gives a perfect (authentic) cadence, V to I. The chords may even inspire you to add a little spice to the melody itself.

Method 2: Cadences and common progressions (ignore the melody)

Here you forget the melody. Instead you try strong, widely used progressions and see which ones fit.

• Authentic cadence V–I (C–F), or flip it to I–V (F–C7). Ending on V is a half cadence.
• Deceptive cadence V–vi (C–Dm). D minor is the relative minor, the second tonic.
• Plagal cadence IV–I (Bb–F), or reverse it to I–IV for a yearning, Lydian-like sound.
• Combine cadences, for example a half cadence followed by a plagal cadence.

Jazz ii–V–I

The major ii–V–I is Gm7 – C7 (or an altered C) – F, Fmaj7 or F6. For a minor ii–V–i, aim at the relative minor, D minor. That gives Em7b5 – A7 – Dm, and you can colour it with A7b9. Try the minor version first, then the major one ending on F.

The four-chord pop progression

Try I–V–vi–IV (F – C – Dm – Bb) and its rotations:

• V–vi–IV–I
• vi–IV–I–V
• IV–I–V–vi

These fit a huge number of melodies. They are less reliable for songs that change key, such as Bohemian Rhapsody or standards like Misty. You can still use ii–V–Is and cadences there, but you have to track the key change.

How to practise

1. Take a simple melody and mark its long, strong-beat notes.
2. List every diatonic chord that contains each marked note.
3. Play several versions and keep the one you like.
4. Then try each cadence, ii–V–I and four-chord rotation under the same tune and compare.

Theory supplies the options, and your ear simply says which one it likes.

Questions about this lesson

Which notes of a melody should I harmonize?

Harmonize the long notes that land on strong beats, such as the first beat of a bar. Short notes between beats act as passing tones and usually do not need their own chord.

What is a chord tree?

A chord tree takes one melody note and branches out to every chord in the key that contains it. In F major, the note C can be harmonized with F major, A minor, C major or D minor 7.

Can I harmonize a melody without analysing it?

Yes. Try common progressions such as V–I, IV–I, ii–V–I or the I–V–vi–IV pop progression and its rotations, then keep whichever your ear prefers. This works best when the song stays in one key.

What is the minor ii–V–i in F major?

Treat the relative minor, D minor, as home. That gives Em7b5 – A7 – Dm, and an A7b9 adds extra colour.

Practise it

• Chord TreesStart from a note and explore related chords, inversions and voicings.
• Cadence LibraryCompare piano cadences across keys and listen to how different chord movements create closure, suspense or a turn in a new direction.
• Piano classes at Nathaniel School of MusicLive online or in Bangalore, with a teacher.
• All free music apps40 practice tools for harmony, rhythm, ear training and more.

Related lessons

• 10 Types of Cadences Explained: Theory, Ear Training and PianoA cadence is a short chord progression of two to four chords, such as V–I (authentic), IV–I (plagal), V–vi (deceptive) or i–bVII–bVI–V (Andalusian), used to end, extend or redirect a musical phrase.
• 5 Ways to Make a Basic Chord Progression Sound BeautifulYou can make a basic two-chord progression like Bb major to D major sound richer by adding passing chords in between: relative minors, plagal (IV) chords, authentic (V) chords, secondary dominants, and ii-V-I approaches to the next chord, all found easily with the Circle of Fifths.
• How to Make I V vi IV Sound Way More Exciting on Piano (5 Methods + Bonus)To make the I V vi IV progression (C, G, Am, F in C major) sound more exciting, keep the four chords but add plagal embellishments, passing bass lines, an epic bVI-bVII cadence, secondary dominants or ii-V-I approaches, or revoice the chords with fifths, sevenths, spread thirds, add2 and sus chords.
• The Mixolydian Cadence: A Bright, Bluesy Piano Progression (bVII–IV–I)The Mixolydian cadence is the chord progression bVII–IV–I built from the major chords of the Mixolydian mode, such as Bb–F–C in C Mixolydian, and it gives the bright, anthemic sound heard in songs like With a Little Help from My Friends.