What is a chord progression?
A chord progression is a sequence of chords played one after another to create harmony in music. Most songs in popular music, jazz, folk, and classical traditions are built on a handful of progressions that have proven to sound satisfying to human ears over centuries of use.
Each chord in a progression comes from the scale of the key you are playing in. When you select a key and scale in this tool, it calculates which chords belong to each scale degree and maps common progressions to their actual chord names. For example, in C Major the I-IV-V-I progression becomes C – F – G – C.
How to read Roman numeral notation
Chord progressions are written using Roman numerals so they can be understood in any key. Uppercase numerals (I, IV, V) indicate major chords. Lowercase numerals (ii, vi) indicate minor chords. A degree symbol (°) indicates a diminished chord.
The numeral tells you the scale degree. I is the root note of the key, IV is the fourth note, V is the fifth, and so on. Because this notation is relative to the key, a I-IV-V-I progression in C Major is C-F-G-C, while the same progression in G Major is G-C-D-G.
Common chord progressions explained
**I – IV – V – I:** The foundation of blues, folk, country, and rock. Three major chords with strong resolution back to the tonic. Heard in thousands of songs across every genre.
**I – V – vi – IV:** The most widely used pop progression of the past few decades. Its circular nature means it can loop indefinitely, creating a familiar and satisfying sound.
**ii – V – I:** The backbone of jazz harmony. The ii chord creates tension, the V chord builds expectation, and the I chord resolves it. Nearly every jazz standard uses this somewhere.
**I – vi – IV – V:** The 1950s doo-wop progression. Creates a nostalgic, cyclical feeling. Also called the "50s progression."
**vi – IV – I – V:** A minor-key feeling variation of the pop progression. Starts on the relative minor, giving it a more emotional or melancholic character.
Scales in this tool
**Major:** The bright, happy-sounding scale most people learn first. Contains seven chords: three major, three minor, and one diminished.
**Minor (Natural):** The darker, more serious-sounding counterpart to major. Used in blues, metal, and emotional ballads. Shares the same chords as its relative major key but arranged differently.
**Dorian:** A minor-sounding mode with a raised sixth degree, giving it a slightly brighter quality than natural minor. Common in jazz, funk, and folk music. The Dorian mode on D uses all the notes of C Major.
**Mixolydian:** A major-sounding mode with a flattened seventh degree. This gives it a bluesy, open quality. Used extensively in rock, folk, and Celtic music.
How to use
1. Select your root key from the dropdown (C, C#, D, and so on through B). 2. Choose a scale: Major, Minor, Dorian, or Mixolydian. 3. The scale chord reference table shows all seven chords in your key, their type, and their notes. 4. Browse the list of common progressions below. Each shows the chord names in your selected key. 5. Press the Play button next to any progression to hear it played through your browser.
FAQs
Q: What does "playable audio preview" mean? A: Each progression has a Play button that uses your browser's built-in Web Audio API to play the chords as triangle wave tones. No plugin or download is needed. The audio approximates the sound of each chord using its root, third, and fifth notes.
Q: What is the difference between major and minor scales? A: Major scales have a bright, happy sound. Minor scales sound darker and more serious. The chords that belong to each scale are different, so the same progression name (like I-IV-V-I) will sound different depending on which scale you choose.
Q: Can I use these progressions on guitar, piano, or any instrument? A: Yes. The chord names shown (like C, Dm, G) are standard chord names that apply to any instrument. The progression works the same whether you are playing guitar, piano, ukulele, or any harmonic instrument.
Q: What is a "scale degree"? A: A scale degree is the position of a note within a scale. In C Major, the first degree (I) is C, the fourth degree (IV) is F, and the fifth degree (V) is G. Roman numeral notation uses these positions so progressions can be described in any key.
Q: Why does the same progression sound different in different keys? A: The relationships between chords stay the same, but the pitches shift. A I-IV-V-I in C uses C-F-G-C. The same progression in D uses D-G-A-D. The emotional quality is similar but the pitch is higher.
Q: What is the Web Audio API? A: The Web Audio API is a built-in browser feature that lets web pages create and manipulate audio without any plugins. This tool uses it to synthesize simple chord tones in real time when you press Play.
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