Chord Chart

How to Use

1. Select a root note (C through B, including sharps and flats) from the note selector buttons.
2. Choose a chord type (Major, Minor, 7th, Maj7, Min7, Dim, Aug, Sus2, Sus4) to see the chord formula and notes.
3. View the guitar fingering diagram and piano keys. Click Play Chord to hear how it sounds.

Chord Theory and Music Harmony

Chords are the harmonic foundation of Western music. The simplest chords are triads—three-note combinations built by stacking intervals of thirds. From any major scale, you can build seven diatonic triads, each with a unique quality: three major (I, IV, V), three minor (ii, iii, vi), and one diminished (vii°). This pattern holds true in every key, which is why the Roman numeral system is used universally to describe chord functions. The circle of fifths organizes all 12 keys by their relationship: moving clockwise adds one sharp (C → G → D → A…), counterclockwise adds one flat (C → F → B♭ → E♭…). Adjacent keys share six of seven notes, making modulation between them smooth and natural. Understanding the circle helps predict which chords sound good together. Common chord progressions appear across genres. The I–IV–V–I progression powers countless rock, pop, and folk songs. The ii–V–I is the cornerstone of jazz harmony—nearly every jazz standard contains it. The I–V–vi–IV progression (C–G–Am–F in C major) appears in hundreds of pop hits from the 1950s to today. The 12-bar blues uses only I, IV, and V chords in a specific pattern that has defined blues, rock and roll, and early jazz since the early 1900s. Seventh chords extend triads by adding a fourth note, creating richer harmonies essential in jazz and R&B. The Nashville Number System, developed by studio musicians in the 1950s, uses Arabic numerals instead of Roman numerals, allowing musicians to transpose songs instantly during recording sessions.

Methodology

All chords are built from intervals measured in semitones (half steps) relative to the root note, following the 12-tone equal temperament system. A major chord combines the root, a major third (4 semitones above root), and a perfect fifth (7 semitones). A minor chord uses a minor third (3 semitones) instead, creating its characteristic darker sound. Seventh chords add a fourth note: dominant 7th uses a minor seventh (10 semitones), while major 7th uses a major seventh (11 semitones). Diminished chords stack two minor thirds (root + 3 + 6 semitones), creating maximum tension. Augmented chords stack two major thirds (root + 4 + 8 semitones), producing an unsettled, dreamy quality. Suspended chords replace the third with either a second (sus2) or fourth (sus4), creating an open, unresolved sound. Guitar diagrams display one common voicing with numbered finger positions, open strings (O), and muted strings (X). Piano views show the chord in root position across one octave. Audio playback synthesizes each note using Web Audio API OscillatorNodes tuned to the correct frequency based on A4 = 440 Hz.

Understanding Your Results

Major chords sound bright and happy—they form the backbone of pop, rock, and country music. Minor chords convey sadness, tension, or introspection and are central to blues, metal, and ballads. Dominant 7th chords create a strong pull toward resolution, making them essential in blues (every chord is a 7th) and jazz turnarounds. Major 7th chords sound lush and dreamy, common in jazz standards and neo-soul. Minor 7th chords blend melancholy with sophistication, widely used in R&B and jazz. Diminished chords create maximum tension and work as passing chords or substitutes for dominant 7ths. Augmented chords produce an unsettled, floating quality heard in film scores and progressive rock. Suspended chords (sus2 and sus4) remove the major/minor quality entirely, creating an open sound that resolves naturally to major or minor. Guitar diagrams: numbered dots show which finger to place (1 = index through 4 = pinky). 'O' means play that string open; 'X' means mute or skip it. Piano views show root position—try moving the lowest note up an octave for inversions that may be easier to play or sound smoother in progressions.

Practical Examples

A songwriter exploring the chord chart discovers that replacing a standard C major with Cmaj7 adds a dreamy quality to their verse, while switching to Am7 in the chorus creates a smooth, melancholic feel common in neo-soul. A guitar student learning barre chords uses the fingering diagram to see exactly where to place each finger for F major—one of the most challenging beginner chords—and compares different voicings up the neck. A piano player preparing for a jazz jam session reviews ii–V–I voicings in several keys, using the audio preview to verify the correct sound before practicing.

Tips for Learning Chords

Start with open chords (C, G, D, E, A, Em, Am, Dm) before attempting barre chords—these use open strings and are easier to play cleanly on guitar. Learn common progressions rather than isolated chords. The I–IV–V and I–V–vi–IV patterns cover a large percentage of popular music and help you understand how chords relate to each other. Use the audio preview to train your ear. Listen to each chord quality (major, minor, diminished, augmented) and learn to recognize them by sound—one of the most valuable skills a musician can develop. When switching between chords on guitar, look for common fingers that stay in place. For example, moving from C to Am, your first and second fingers barely move. Practice transitions slowly before building speed. Piano players should experiment with inversions beyond root position. Root position chords require large hand jumps, while inversions keep your hand in one area of the keyboard. Try a C–F–G progression using inversions: C (C-E-G), F (C-F-A), G (B-D-G)—your hand barely moves.

Sources

• Music Theory – Chord Construction
• Musical Intervals Reference
• Chord Progressions in Popular Music
• W3C Web Audio API Specification