Blog

How to Read Roman Numerals & Build Your Own Chord Progressions (Piano-Friendly Guide)

Ever wonder how songs are built—or how to create your own? Roman numerals are the key. Let’s break them down.
Once you understand how to read Roman numerals, you can decode almost any chord progression, play by ear more easily, and even write your own songs in any style.

What Are Roman Numerals in Music?

Roman numerals are a way to represent chords relative to the scale instead of using specific note names.

  • Uppercase numerals = major chords
  • Lowercase numerals = minor chords
  • ° symbol = diminished chords

Example – C Major Scale
 C – D – E – F – G – A – B – C
I – ii – iii – IV – V – vi – vii° – I

Example – A Minor Scale
 A – B – C – D – E – F – G – A
i – ii° – III – iv – v – VI – VII – i

This system works for any key, making it a universal “map” for music.

How to Build Chords from Roman Numerals

To build a chord for each numeral, start with the scale note and stack every other note until you have three notes (a triad).

Example in C Major:

  • I (C major) – C – E – G
  • ii (D minor) – D – F – A
  • iii (E minor) – E – G – B
  • IV (F major) – F – A – C
  • V (G major) – G – B – D
  • vi (A minor) – A – C – E
  • vii° (B diminished) – B – D – F

Visual Tip: On the piano, mark the root note in one color, the third in another, and the fifth in another to train your eyes and fingers.

Common Chord Progressions

Here are some progressions you’ve probably heard a million times:

  • I–V–vi–IV – The pop hitmaker progression (Example in C: C–G–Am–F)
  • I–IV–V–I – Folk and classical favorite (C–F–G–C)
  • ii–V–I – Jazz standard turnaround (Dm–G–C in C major)

Play each one in different keys to train your ear and fingers.

How to Practice with Roman Numerals

  1. Pick a key and write out its scale degrees with numerals.
  2. Map out chords for each degree.
  3. Play progressions in that key.
  4. Transpose the progression into new keys.
  5. Improvise melodies over the chords.
  6. Challenge yourself with flashcards or random progression generators.

Why It Matters

Learning Roman numerals is like learning music’s native language. It helps you:

  • Write songs faster
  • Play by chord charts
  • Understand music theory in context
  • Transpose to new keys instantly
  • Build better ear training skills

Pro Tip: Start labeling every chord you learn with Roman numerals. Soon, you’ll think in progressions instead of just notes, making it much easier to play and create in any style.