Progressão de Acordes (I-IV-V)

Chord progressions, in plain Roman numerals

A chord progression is a sequence of harmonies that gives a song direction. Music theory labels each chord by its scale degree using Roman numerals so that the same progression can be transposed to any key without rewriting names. In the key of C major, the diatonic chords are I = C, ii = Dm, iii = Em, IV = F, V = G, vi = Am, and vii° = Bdim. Uppercase numerals are major chords; lowercase are minor; the circle marks a diminished chord. Move the same shape to G major and you get G, Am, Bm, C, D, Em, F#dim — the relationship is identical even though every chord name changed.

A handful of progressions account for the majority of pop hits. I-V-vi-IV is the "Axis of Awesome" progression behind Don't Stop Believing, Let It Be, With or Without You and No Woman No Cry. I-IV-V is the backbone of the 12-bar blues, rock and roll and most country. ii-V-I is the cadence every jazz student memorises first. vi-IV-I-V drives Despacito, Faded and Africa. I-vi-IV-V — the doo-wop progression — defined 1950s pop and reappears in Stand By Me and Earth Angel.

Tonal functions: tonic, subdominant, dominant

Every diatonic chord falls into one of three functional roles. The tonic (I, iii, vi) is home — it sounds stable and resolved. The subdominant (ii, IV) moves away from home, creating motion. The dominant (V, vii°) creates tension that wants to resolve back to the tonic. Almost every progression is a journey through these three functions. The classic resolutions are cadences: perfect V-I (final, conclusive), plagal IV-I (the "amen" cadence), interrupted V-vi (deceptive, sets up another phrase) and half any-V (suspended, often closing a verse).

Advanced moves: secondary dominants, borrowed chords, tritone substitution

Once the diatonic palette feels small, composers reach for outside colours. A secondary dominant (notated V/V, "five of five") borrows the dominant of a non-tonic chord to set it up: in C major, D7 is V/V because it resolves naturally to G. Borrowed chords import a chord from the parallel minor — using iv (Fm) or bVII (Bb) inside C major adds melancholy without modulating. Modal interchange generalises the idea to any parallel mode. Tritone substitution, central to jazz, replaces a dominant chord with the one a tritone away that shares its guide tones: G7 becomes Db7, and the bass walks down chromatically into C.

Tools and software for studying progressions

Online, Hooktheory publishes statistics on which progressions appear in which Billboard hits, and Chordify auto-detects chords from any YouTube clip. For composing, every modern DAW — GarageBand, Reaper, Ableton Live, FL Studio, Logic Pro — ships with chord track generators or MIDI plugins like Scaler 2 that suggest diatonic continuations. iReal Pro is the go-to for jazz musicians learning real-book changes.

FAQ

Can I compose a song with any chord progression? In principle yes, but coherence matters: the ear needs a sense of home and motion. Random progressions sound disjointed. Start with a tried-and-tested skeleton (I-V-vi-IV is unbeatable for pop) and only break it once you understand why it works.

Does the key affect how the progression sounds? The interval relationships do not change — I-V-vi-IV in C and in G feel identical melodically. What changes is timbre on instruments: open-string keys (E, A, G, D) ring brighter on guitar; piano keys with black notes (Db, F#) feel different under the fingers.

Which progression should a beginner start with? I-V-vi-IV for pop and singer-songwriter material, or I-IV-V for blues, rock and country. Both unlock thousands of songs immediately and are the foundation for every more complex idea.

What is the difference between V and V7? V is a plain major triad on the fifth degree (G, B, D in C major). V7 adds the flat-seven (G, B, D, F), which creates a stronger pull to the tonic because the F-B tritone wants to resolve to E-C. Most pop uses plain V; blues and jazz prefer V7 for the extra tension.