Nathaniel School of Music

How to Build Chords for Any Melody on Piano (Cadences and Music Theory)

To harmonise any melody on piano, start by adding fifths and thirds under each melody note, then choose chords using cadences such as V–I, ii–V, V–vi and IV–I, and add colour with line cliché basses, secondary dominants, ii-V-I movements and chords borrowed from the parallel minor.

Video lesson by Jason Zac · Intermediate · 31 min

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Key points

This lesson by Jason Zac of Nathaniel School of Music shows how to put chords under a melody, step by step. It uses one very simple tune so the focus stays on harmony. It suits students who can already play basic triads and want a roadmap for harmonising songs in classical, pop, jazz, gospel and film styles.

The melody

The tune is in Eb major (three flats: Eb, Ab and Bb) and uses only scale degrees 1, 2 and 3: Eb F G G F Eb Eb. Play it over a steady pulse first, and sing it with numbers or swaras until it feels secure.

Step 1: Fifths (power chords)

The simplest harmony is a fifth chord: root, fifth and octave. Stack a fifth with each melody note (Eb with Bb, F with C, G with D) and the tune already sounds thicker. You can also hold the tonic fifth (Eb and Bb) and build arpeggios around it while the melody rests, or colour it by moving to other scale notes such as the seventh, sixth and fourth before returning to the fifth. Fifths work with almost any melody, but they offer few harmonic choices, so you need to expand.

Step 2: Thirds below the melody

Take the note a third above each melody note and play it an octave lower, under the tune, like a tenor part in a choir: G under Eb, Ab under F, Bb under G. The melody stays on top and the sound becomes richer.

Step 3: The four classical cadences

How to play chords with the melody

  1. New players: melody in the right hand, just the chord roots in the left hand.
  2. Next stage: melody in the right hand, full chords in the left hand.
  3. Advanced: play the whole chord in the right hand as an inversion, keeping the melody note on top, while the left hand plays deep roots. This needs finger independence, not just hand independence.

Step 4: Line cliché and climbing chords

Let the bass move chromatically while the melody stays the same. For example, drop from Eb down to Ab: Eb, D, Db, C, B, Bb, A, Ab. Each step is really a chord (such as Gm over D, or Ab over C), but you can simply think of it as a falling bass, in octaves or with your little finger on the bass note. You may skip steps.

You can also climb: Cm, Bb/D, Eb, Eb/G, Ab, F/A, Bb. The connecting chords work because they are dominants of the next chord; Bb/D leads to Eb because Bb is the fifth of Eb.

Step 5: Secondary dominants

Approach any diatonic chord with its own dominant, a chord from outside the scale:

Step 6: Major and minor ii-V-I

Major: Fm, Bb7, Eb. For a jazzier dominant, play Ab over Bb for a ninth or eleventh feel. Minor, aiming at the relative minor Cm: Ddim, G7, Cm.

Step 7: Borrowed chords

From Eb natural minor come bIII, bVI and bVII, all major chords: Gb, Cb (B) and Db.

How to practise

Work through one idea at a time on this three-note tune: fifths, thirds, then each cadence, first with roots only, then full chords. Once comfortable, try the right-hand inversion approach and the more colourful options. Note that iv to i will not fit this melody, because the tune contains the major third, G.

Questions about this lesson

What is the easiest way to add chords to a melody on piano?

Play the melody in the right hand and only the chord roots in the left hand. Once that is steady, replace the roots with full chords in the left hand.

What are the four classical cadences?

The authentic cadence (V to I), the half cadence (any chord ending on V, such as ii–V or IV–V), the deceptive cadence (V to vi) and the plagal cadence (IV to I). In Eb major these are Bb–Eb, Fm–Bb or Ab–Bb, Bb–Cm and Ab–Eb.

What is a line cliché bass?

It is a bass line that moves chromatically down or up step by step while the melody stays the same, for example Eb, D, Db, C, B, Bb, A, Ab under the tune. Each bass note implies a chord, but you can think of it simply as a moving bass.

How do secondary dominants help harmonise a melody?

A secondary dominant is the V chord of another chord in the key, such as D7 leading to Gm or C7 leading to Fm in Eb major. It brings in a chord from outside the scale that resolves strongly to a chord within it, though you may need to adjust a melody note slightly to fit.

Practise it

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