Progressions and transposing

The same progression can be played in any key. By writing it with Roman numerals, you can move it to a new key by swapping the key and keeping the numerals. This is how singers get songs into their range and how guitarists use a capo.

By the end of this lesson you will be able to:

• Write a progression with Roman numerals.
• Transpose a progression to a new key.
• Use a capo to transpose without changing shapes.

A progression is a sequence of chords. Written in Roman numerals, it no longer belongs to one key. I V vi IV is the same progression in every key. To play it in G, you replace each numeral with its chord in G.

Transposing means moving a piece to a new key while keeping all its relationships. The method:

1. Write the progression in numerals.
2. Choose the new key.
3. Write the chord for each numeral in that key.

Why do it? A singer might find a song too high or low. You might find a key easier on the guitar. Or you might be playing with someone who plays in a different key.

The capo transposes without changing shapes. A capo at fret 2 raises every chord by two semitones. Play G, D, Em and C shapes with a capo at 2 and they sound as A, E, F♯m and D.

I V vi IV in five keys:

• C: C, G, Am, F
• G: G, D, Em, C
• D: D, A, Bm, G
• A: A, E, F♯m, D
• E: E, B, C♯m, A

I vi IV V (the ’50s progression):

• C: C, Am, F, G
• G: G, Em, C, D
• D: D, Bm, G, A
• A: A, F♯m, D, E

Transposing a song. Stand By Me is A, F♯m, D, E.

1. Write the numerals: A is I, F♯m is vi, D is IV, E is V.
2. For the key of G: I is G, vi is Em, IV is C, V is D. The song becomes G, Em, C, D.
3. Play it. It is the same song, one tone lower, and uses only open chords.

To play it in A with those open G shapes, put a capo at fret 2. The shapes G, Em, C and D then sound A, F♯m, D and E.

Do these in order. Each one is small. Tick the ones you have practised.

• 1.Write it in numerals

  4 min

  1. Take the verse of Let It Be: C G Am F, in C major. Write its Roman numerals: I V vi IV.
  2. Take Knockin' on Heaven's Door in G: G D Am, then G D C. Write its numerals: I V ii, then I V IV.
  3. Take Stand By Me in A: A F♯m D E. Write its numerals: I vi IV V.

  You have it when

  • You write each numeral correctly, with the right case.
  I practised this one

• 2.Transpose I–V–vi–IV

  5 min · 60 → 90 BPM

  1. Play I V vi IV in C: C G Am F.
  2. Play it in G: G D Em C.
  3. Play it in D: D A Bm G.
  4. Play it in A: A E F♯m D.

  You have it when

  • You can play the progression in four keys and name the chords from the numerals alone.
  I practised this one

• 3.Capo shortcut

  4 min

  1. Play G D Em C with no capo.
  2. Put a capo at fret 2 and play the same shapes. The chords now sound as A E F♯m D.
  3. Find the capo position that moves the progression to the key of B (fret 4).

  You have it when

  • You can explain that a capo raises every chord by one semitone per fret.
  I practised this one

Play at 70 to 90 BPM, four beats per chord. Take your time in unfamiliar keys: the unfamiliar chords matter more than tempo.

• Transposing chord by chord. Use the numerals. Pick the key, then read off the chords.
• Forgetting that numerals only name the chord's role, not its quality. Upper case is major, lower case is minor. That tells you the quality.
• Using the wrong capo fret. Capo fret = number of semitones up. To go from G shapes to A, use fret 2; to B, fret 4.

Let It Be (C) and Stand By Me (A) use the I–V–vi–IV and I–vi–IV–V families. You can play either in any key you choose, and you now know how to change the key to suit a voice.

Try it in: Let It Be, Stand By Me.

Short version (10 minutes)

Play I V vi IV in G and then in D, four beats per chord.

Standard version (about 30 minutes)

Do all three exercises, then choose a song from the library and play it in a key one step higher.

• Roman numerals describe a progression independent of key.
• Transposing means choosing a new key and keeping the numerals.
• A capo raises all chords by a semitone per fret.
• I V vi IV and I vi IV V are the two most common pop progressions.

You are ready to move on when you can honestly say:

• I can write a progression using Roman numerals.
• I can transpose it into at least three keys.
• I can use a capo to change the key without changing shapes.