You hear a song that moves you — something about the chords creates a feeling you want to understand and eventually recreate in your own music. But staring at a chord chart and asking “why does this work?” can feel overwhelming without a system. The good news is that harmonic analysis follows a clear process, and once you have the steps down, you can decode the harmony of virtually any song in any genre.
Here is a five-step framework you can apply right away.
Step 1: Identify the Key
Before you can say anything meaningful about a song’s chords, you need to know what key it is in. The key establishes the “home base” — the set of notes and chords that feel resolved and stable.
Start with the first and last chords. Songs overwhelmingly begin and end on the tonic chord (the I chord). If a song starts on G and ends on G, G major is your strongest guess for the key.
Look at the bass note of the final chord. Even when the ending chord is not immediately obvious, the lowest note at the very end of the song almost always confirms the tonic.
Check for sharps and flats. If the chords include F♯m and C♯m but no flats, you are likely in A major or its relative F♯ minor. A quick glance at the circle of fifths can confirm which key signature matches the accidentals you see.
Determine major or minor. If the tonic chord is major and the overall mood feels bright, it is a major key. If the tonic chord is minor and the mood is darker, it is the relative minor. Songs in A minor and C major share the same notes but feel very different because of where the harmony resolves.
| Clue | Points to major key | Points to minor key |
|---|---|---|
| Tonic chord quality | Major | Minor |
| Presence of V7 resolving to I | V7 → I (e.g., G7 → C) | V7 → i (e.g., E7 → Am) |
| Emotional quality | Bright, resolved | Dark, tense |
| Leading tone usage | Frequent | May appear as ♭VII instead |
If you are unsure, open the Interactive Chord Finder, try both the major scale and the natural minor scale on your suspected root note, and see which diatonic chord table matches more of the song’s chords.
Step 2: Label Every Chord with a Roman Numeral
With the key established, assign a Roman numeral to each chord based on which scale degree it is built on. This is the core of harmonic analysis — it tells you the function of each chord, not just its name.
In C major, the diatonic chords are:
| Degree | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| Chord | C | Dm | Em | F | G | Am | Bdim |
If the song uses C – Am – F – G, the analysis reads I – vi – IV – V. Now you can see the progression’s function regardless of key. This same pattern in E major would be E – C♯m – A – B — different chords, identical function.
For seventh chords, add the appropriate symbol: Cmaj7 = Imaj7, Dm7 = ii7, G7 = V7. The process is the same — identify the root, find its position in the scale, and label it.
Write the analysis underneath each chord. Your chart should look something like:
| C | Am | F | G |
| I | vi | IV | V |
This notation is compact, transportable, and immediately reveals the harmonic structure.
Step 3: Spot Non-Diatonic Chords
Most pop, rock, and folk songs stay entirely within the diatonic chords of one key. But many songs include one or two chords that do not belong to the key. Identifying these is where the analysis gets interesting.
Common non-diatonic chord types:
Secondary dominants are major or dominant seventh chords built on a degree that would normally be minor or diminished. In C major, an A7 chord is V/ii — the dominant of Dm. It borrows the leading-tone resolution from D minor’s key to pull strongly toward Dm.
Borrowed chords (modal interchange) come from the parallel key. In C major, a song might use A♭ (♭VI), B♭ (♭VII), or Fm (iv) — all borrowed from C minor for a momentary darker colour.
Chromatic passing chords appear between two diatonic chords. A C♯dim between C and Dm creates a chromatic bass line (C – C♯ – D) that smooths the movement.
When you encounter a chord that does not fit the diatonic set, ask: “Is this a secondary dominant? A borrowed chord? A chromatic passing chord?” Label it accordingly.
| Symbol | Meaning | Example in C major |
|---|---|---|
| V/V | Secondary dominant of V | D or D7 (targeting G) |
| V/ii | Secondary dominant of ii | A or A7 (targeting Dm) |
| ♭VII | Borrowed from parallel minor | B♭ |
| iv | Borrowed from parallel minor | Fm |
| ♭VI | Borrowed from parallel minor | A♭ |
Step 4: Identify Structural Sections
Harmony does not exist in isolation — it serves the song’s form. Once you have labelled every chord, zoom out and look at how the harmony shapes the sections.
Verse harmony is often more restrained, using fewer chords or repetitive patterns to keep focus on lyrics and melody.
Chorus harmony frequently includes the strongest resolution (V → I) and the most forward-driving chord choices.
Bridge harmony is where songwriters introduce the most surprising chords — borrowed chords, secondary dominants, and key changes appear most often here because the section’s job is to provide contrast.
Pre-chorus sections commonly use rising harmonic tension — ascending bass lines or sustained V chords — to build anticipation for the chorus.
Map out the song’s sections and note which chords belong to which part. You will start to see patterns: maybe the verse circles through I – V – vi – IV while the chorus flips to IV – V – I – I. That difference in chord ordering is what makes the chorus feel different from the verse, even though the same four chords appear in both.
Step 5: Ask “Why Does This Work?”
This is the step that transforms mechanical labelling into genuine understanding. For each notable harmonic moment, ask what the chord is doing — what tension it creates, what expectation it sets up, and how it resolves (or deliberately avoids resolution).
Some questions to guide you:
Does the progression create tension and release? The motion from V7 to I is the strongest resolution in Western harmony. If a song withholds this resolution — ending phrases on IV instead — that avoidance creates openness or yearning.
Where do the surprises happen? A sudden ♭VI chord in a major-key song catches the ear because it is unexpected. Noting where in the form these surprises land reveals the songwriter’s craft.
How does the bass line move? Smooth, stepwise bass motion often explains why an unusual chord choice works. A chord that seems random on paper may exist to create a logical bass line.
Is there a pattern of tension escalation? Many songs increase harmonic tension through the verse and pre-chorus, peak at the chorus, and then resolve.
Putting It All Together: A Quick Example
Imagine a song with these chords:
Verse: G – D/F♯ – Em – C Chorus: C – D – G – Em – C – D – B7 – Em
Step 1: The song starts and ends sections on G and Em. Given the overall bright feel, the key is G major.
Step 2: Label the diatonic chords.
| Section | Chords | Analysis |
|---|---|---|
| Verse | G – D/F♯ – Em – C | I – V⁶ – vi – IV |
| Chorus | C – D – G – Em – C – D – B7 – Em | IV – V – I – vi – IV – V – III7 – vi |
Step 3: B7 does not belong to G major (the diatonic iii chord is Bm, not B major). B7 functions as V/vi — a secondary dominant targeting Em. It intensifies the pull toward the vi chord.
Step 4: The verse uses a descending bass line (G – F♯ – E – C) for smooth voice leading. The chorus uses IV – V – I resolution twice, redirecting to vi via the secondary dominant the second time.
Step 5: The B7 → Em at the end of the chorus is the emotional peak — by momentarily treating Em as a temporary tonic, the songwriter adds darkness right before the song cycles back to the verse.
Where to Go from Here
Harmonic analysis draws on nearly every fundamental concept in music theory. If any step felt unfamiliar, revisiting the major scale, diatonic chords, and chord progressions will strengthen your foundation. For songs with richer harmony, understanding seventh chords and extended chords will help you label more complex sonorities.
Pick a song you love, pull up its chords, and work through the five steps. Use the Interactive Chord Finder to verify diatonic chords in any key — select the root and scale, and the diatonic chord table becomes your instant reference. The more songs you analyse, the faster you will recognise common patterns, and the more those patterns will inform your own writing and playing.
Practice Chords
Drill chord recognition with a metronome, MIDI support, and score tracking.
Start Practicing
