Chord Finder from Notes

How to Identify a Chord from Its Notes: A Practical Guide

"What chord is this?" is one of the most common questions asked by guitarists, pianists, producers, and students the moment they discover a combination of notes that sounds interesting. Western harmony contains hundreds of named chord types, and even experienced musicians are not always certain whether a cluster of notes is a dominant seventh, a minor-major seventh, or an added ninth. This tool removes the guesswork. Select the notes you are playing and the chord finder runs every possible chord formula against your input, returning a ranked list of matches in under a second.

How Chord Detection Works

Every chord is defined by a set of intervals measured in semitones from a root note. A major triad is always the root (1), the major third (4 semitones above the root), and the perfect fifth (7 semitones above the root). A minor triad swaps the major third for a minor third (3 semitones). A dominant seventh adds a minor seventh (10 semitones) on top of a major triad.

This tool uses the Tonal.js library, an open-source music theory engine that covers over 300 chord types. When you select notes, the engine tries every possible root from the 12 chromatic pitches, applies each chord formula, and checks whether the resulting note set matches your input. A result labeled Exact means your notes and the chord notes are identical. A result labeled Partial means your notes are all present in the chord, but the chord contains additional tones you have not selected.

This distinction matters in practice. If you play C, E, and G, the tool returns C major as an exact match. It also returns Cmaj7, C6, C6/9, Cadd9, and other partial matches, because all those chords contain C, E, and G alongside additional notes. Adding the note B to your selection narrows it to Cmaj7 as the exact match, which is exactly how a musician would reason through the question on paper.

Chord Categories and What They Mean

The filter buttons group chords into five practical categories. Understanding each one makes the results easier to navigate.

Triads are three-note chords built from a root, a third, and a fifth. They are the simplest complete harmonic statement in Western music. Major (C E G), minor (C Eb G), diminished (C Eb Gb), and augmented (C E G#) are the four triad qualities. Sus2 (C D G) and sus4 (C F G) suspend the third, replacing it with the second or fourth. Triads are the building blocks of all more complex chords.

Seventh chords add a fourth note, one third above the fifth, to a triad. The dominant seventh (C E G Bb, written C7) is the most harmonically active chord in Western music. Its tension consistently resolves down a fifth to the tonic. The major seventh (C E G B, written Cmaj7) sounds sophisticated and stable, widely used in jazz, soul, and R&B. The minor seventh (C Eb G Bb, written Cm7) is the foundation of ii-V-I progressions in jazz. The half-diminished (C Eb Gb Bb, written Cm7b5) and fully-diminished (C Eb Gb A, written Cdim7) chords appear in both classical and jazz contexts, most often as leading-tone chords or passing harmonies.

Extended chords continue stacking thirds beyond the seventh: ninths, elevenths, and thirteenths. A C9 chord is C E G Bb D. A C13 chord theoretically contains all seven notes of the scale voiced simultaneously. In practice, players omit some tones for playability, which is why the partial match feature is useful: you can select just the notes you are actually playing and see which extended chord they represent.

Suspended chords replace the third with the second (sus2) or fourth (sus4). Because the third is what defines a chord as major or minor, suspended chords have an open, unresolved quality. They appear throughout pop, rock, and folk music as a way to add texture without committing to a particular chord quality. Dsus2 (D E A) and Dsus4 (D G A) are extremely common in guitar-based music.

Diminished and augmented chords are both built on altered fifths. The diminished fifth (tritone) gives diminished chords their unstable, tense sound. Fully diminished seventh chords (such as Bdim7: B D F Ab) are symmetrical, meaning every inversion of the same chord is enharmonically equivalent to another diminished seventh. Augmented chords raise the fifth by a semitone, giving them a dreamy, unresolved quality often used before a dominant chord in jazz and classical music.

Inversions, Slash Chords, and Voicing

A chord inversion occurs when a note other than the root is in the bass. C major in first inversion (E in the bass) is written C/E. The notes C, E, and G are the same, but the harmonic weight shifts. Slash chords like G/B (G major with B in the bass) are common in smooth bass line movements and are listed separately in the results when detected. The interval display for each result makes it straightforward to identify which note functions as the bass tone.

Voicing refers to the specific octave placement and distribution of chord tones. Open voicings spread notes across a wider range; close voicings stack them within a single octave. This tool identifies chords by pitch class rather than octave, so it correctly identifies a chord regardless of how its notes are voiced across the instrument.

Using the Results for Songwriting and Theory

Knowing the name of a chord is the first step. Knowing what to do with it is the practical payoff. Once you identify a chord, you can use the Key and Scale Finder to see which keys that chord belongs to. If C, E, and G form a C major triad, C major appears in the keys of C major (as the I chord), G major (as the IV chord), F major (as the V chord), A minor (as the III chord), E minor (as the VI chord), and D minor (as the VII chord). That list immediately suggests several keys your song might be in, which then tells you which other chords will sound natural alongside it.

The Chord Wheel shows these relationships visually using the circle of fifths, making it easy to spot the chords that naturally lead into and out of your identified chord. If you need to move the chord to a different key for a vocalist, the Chord Transposition Tool handles the calculation instantly.

Common Identification Scenarios

Transcribing by ear: You have worked out the notes of a chord from a recording but cannot name it. Enter the notes here to get the name, then cross-reference the result with the Nashville Number Converter to understand its harmonic function in the key of the song.

Producing on a keyboard roll: MIDI production often involves stacking notes without thinking about chord names. Identifying the chords you have built gives you vocabulary to communicate with collaborators and helps you understand why certain note combinations work.

Learning from a chart: A lead sheet or chord chart shows you chord symbols, but you may not know exactly which notes those symbols contain. Use the tool in reverse: if you know it is an Am7b5, select A, C, Eb, G to confirm the notes before you play.

Analyzing harmony: Music students and arrangers can input notes from specific beats in a score to identify chromatic alterations, borrowed chords, and secondary dominants that might not be immediately obvious from the notation.

Why Some Note Sets Return Many Matches

Two or three notes will always return a large number of results because many different chords share those notes. C and E appear in Cmaj7, C6, Cadd9, Am7, C major, and A minor (when the A is in the bass). This is not a flaw in the detection, it is a reflection of how harmonic ambiguity works in music. Context, especially the bass note and the surrounding chords, determines which interpretation is correct. Adding more notes rapidly reduces the number of matches. Four specific notes usually narrow the results to a handful of closely related chords. Five or more notes will most often produce a single exact match.

Frequently Asked Questions

How many notes do I need to enter?
Two notes show all chords that contain both pitches, which is a large set. Three notes reduce the results significantly. Four or five notes usually isolate the chord precisely.

What is the difference between Bb and A#?
They are the same pitch on an equal-tempered instrument, called enharmonic equivalents. This tool treats them identically. The buttons use sharp spellings (A#) for consistency, but you can type Bb in the text input and it will be correctly normalized.

Why does a partial match appear if I have not selected all the notes?
A partial match means your selected notes are all contained within that chord, but the chord also includes notes you have not selected. For example, selecting C and E returns Cmaj7 as a partial match because Cmaj7 contains C, E, G, and B. You have covered two of the four tones.

Can this tool identify slash chords?
Yes. Slash chords like G/B or D/F# are detected when the note set matches an inversion of a known chord. The symbol displayed will include the bass note after the slash.

Is this tool free?
Yes. It runs entirely in your browser, requires no account, and has no usage limits.