About

Misidentifying a chord costs rehearsal time and produces arrangement errors that compound across a full score. This tool computes chord tones from first principles: a root note plus a set of intervals measured in semitones above the chromatic scale. It covers 19 chord qualities across all 12 roots (228 chords total), rendering both guitar fretboard voicings and piano key maps. Audio playback uses triangle-wave oscillators at A4 = 440 Hz equal temperament. The tool approximates standard open and barre voicings for guitar. Some enharmonic spellings are simplified (e.g., E♭ shown as D♯ internally). For jazz extensions beyond the 13th, consult a dedicated voicing reference.

Formulas

Every chord is constructed by stacking intervals above a chosen root. The frequency of each note in 12-tone equal temperament is:

f_n = f₀ × 2ⁿ¹²

Where f₀ = 440 Hz (A4 concert pitch) and n is the number of semitones from A4. For a major triad, the intervals are 0, 4, 7 semitones. For C major: root = C, third = E (root + 4), fifth = G (root + 7). Guitar standard tuning is E2-A2-D3-G3-B3-E4 corresponding to MIDI notes 40-45-50-55-59-64.

Reference Data

Chord Type	Symbol	Intervals (semitones)	Formula (degrees)	Character
Major	C	0-4-7	1 3 5	Bright, stable
Minor	Cm	0-3-7	1 ♭3 5	Dark, sad
Dominant 7th	C7	0-4-7-10	1 3 5 ♭7	Bluesy, tense
Major 7th	Cmaj7	0-4-7-11	1 3 5 7	Smooth, jazzy
Minor 7th	Cm7	0-3-7-10	1 ♭3 5 ♭7	Mellow, warm
Diminished	Cdim	0-3-6	1 ♭3 ♭5	Tense, unstable
Diminished 7th	Cdim7	0-3-6-9	1 ♭3 ♭5 ♭♭7	Symmetric, eerie
Augmented	Caug	0-4-8	1 3 ♯5	Dreamy, unresolved
Augmented 7th	Caug7	0-4-8-10	1 3 ♯5 ♭7	Altered dominant
Suspended 2nd	Csus2	0-2-7	1 2 5	Open, ambiguous
Suspended 4th	Csus4	0-5-7	1 4 5	Hymn-like, floating
Add 9	Cadd9	0-4-7-14	1 3 5 9	Shimmering, pop
Dominant 9th	C9	0-4-7-10-14	1 3 5 ♭7 9	Funky, rich
Minor 9th	Cm9	0-3-7-10-14	1 ♭3 5 ♭7 9	Neo-soul, lush
Dominant 11th	C11	0-4-7-10-17	1 3 5 ♭7 11	Complex, modal
Dominant 13th	C13	0-4-7-10-21	1 3 5 ♭7 13	Full, orchestral
Major 6th	C6	0-4-7-9	1 3 5 6	Vintage, happy
Minor 6th	Cm6	0-3-7-9	1 ♭3 5 6	Bossa nova, wistful
Power Chord	C5	0-7	1 5	Neutral, heavy

Frequently Asked Questions

Timbre differs because of harmonic overtone structure, but voicing also matters. A guitar C major in open position places the notes E2-C3-E3-G3-C4-E4 across six strings, spanning nearly three octaves. A keyboard player typically voices C4-E4-G4 in a single octave. Wider voicings create more spacious sounds. The chord finder shows the exact pitches per instrument so you can compare.

C9 includes the dominant 7th (B♭) making its interval set 0-4-7-10-14 semitones. Cadd9 omits the 7th entirely - its intervals are 0-4-7-14. The presence of the ♭7 in C9 creates a dominant function that wants to resolve, while Cadd9 is stable and commonly used in pop and acoustic music.

In equal temperament every semitone ratio is exactly 2^(1/12) ≈ 1.05946. A pure major third should be a 5:4 frequency ratio (1.25000), but the tempered third is 2^(4/12) ≈ 1.25992 - about 13.7 cents sharp. This is why major chords on a piano have a slight "beating" quality compared to just intonation. The tool uses strict equal temperament for universal compatibility.

Yes. A diminished 7th chord is symmetric - it divides the octave into four equal minor thirds (0-3-6-9 semitones). Any note in the chord can function as a leading tone. For example, B-dim7 (B-D-F-A♭) shares three notes with G7♭9 (G-B-D-F-A♭), making it a common substitution that adds chromatic tension.

Not all six strings can produce chord tones without introducing unwanted notes. For a D major chord (D-F♯-A), the low E and A strings would add E2 and A2 - the 2nd and 5th degrees - muddying the bass. Muting them keeps the root D in the bass for a cleaner voicing. The diagram marks muted strings with an X above the nut.

Convention follows the key signature context. This tool defaults to sharps for most roots but uses flats for traditional flat-key roots (F, B♭, E♭, A♭, D♭, G♭). Enharmonic equivalence means D♯ and E♭ produce identical frequencies at 311.13 Hz. The spelling choice affects readability in staff notation but not the sound.