Tools
Chord identifier
Name a chord from its notes. Tap them on the keyboard or type them in, and read back the chord symbol, its inversion and every other name the same notes can take — with its formula, its notation and its sound.
The chord’s name will appear here.
How chords are built
A chord is a stack of thirds on a root. Take a note, add the note a third above, then a third above that, and you have a triad. Which thirds — major (four semitones) or minor (three) — decides its quality: major third then minor third is a major triad, C E G; minor then major is minor, C E♭ G; two minor thirds are diminished, C E♭ G♭; two major thirds are augmented, C E G♯.
One more third gives a seventh chord, and the seventh’s size names it. C E G B is a major seventh, Cmaj7; C E G B♭ a dominant seventh, C7; C E♭ G B♭ a minor seventh, Cm7; C E♭ G♭ B♭ a half-diminished, Cm7♭5; C E♭ G♭ B♭♭ a diminished seventh, C°7.
Keep stacking and you reach the extensions, named for their distance from the root: the ninth, eleventh and thirteenth. C9 is C7 with a D on top. A chord that skips the seventh and adds a ninth is written add9; one that replaces the third with a second or a fourth is a suspended chord, sus2 or sus4. The tool reads every one of these from the notes alone, so the name it gives is only ever a description of what you played.
Inversions and slash chords
A chord keeps its name whatever order its notes are played in, but the note at the bottom changes how it sounds, and that note has a name of its own. With the root at the bottom the chord is in root position. With the third at the bottom it is in first inversion; with the fifth, second inversion; with the seventh, third inversion.
Chord charts write an inversion as a slash chord: the chord, a slash, the bass note. C/E is a C major triad with E in the bass — first inversion — and C/G has G in the bass. The tool reads the lowest note you tap, or the first note you type, as the bass, and names the chord accordingly; the reference table below shows the three positions of one triad.
| Notes, bass first | Symbol | Position |
|---|---|---|
| C E G | C | Root position |
| E C G | C/E | First inversion |
| G C E | C/G | Second inversion |
A worked example
E G♯ B D→E7
- Find the bass. The notes are E, G♯, B and D, lowest first, so E is the bass and the first root to try.
- Stack thirds from it. E to G♯ is a major third, G♯ to B a minor third, B to D another minor third: a major triad with a minor seventh on top.
- Name the stack. Major triad plus minor seventh is a dominant seventh chord, formula 1 – 3 – 5 – ♭7, so the notes spell E7.
- Check the bass. Had D been the lowest note, the same four notes would be E7 in third inversion, written E7/D. The tool shows that name too, under the other names.
Common chord types
The chord types the tool names most often, each with its interval formula and its notes on C. The formulas are computed by the same library the tool runs, so a name here is exactly what the tool would give for those notes.
| Chord type | On C | Formula | Notes |
|---|---|---|---|
| Major | C | 1P · 3M · 5P | C E G |
| Minor | Cm | 1P · 3m · 5P | C E♭ G |
| Diminished | Cdim | 1P · 3m · 5d | C E♭ G♭ |
| Augmented | Caug | 1P · 3M · 5A | C E G♯ |
| Suspended 2 | Csus2 | 1P · 2M · 5P | C D G |
| Suspended 4 | Csus4 | 1P · 4P · 5P | C F G |
| Fifth | C5 | 1P · 5P | C G |
| Sixth | C6 | 1P · 3M · 5P · 6M | C E G A |
| Minor sixth | Cm6 | 1P · 3m · 5P · 6M | C E♭ G A |
| Dominant seventh | C7 | 1P · 3M · 5P · 7m | C E G B♭ |
| Major seventh | Cmaj7 | 1P · 3M · 5P · 7M | C E G B |
| Minor seventh | Cm7 | 1P · 3m · 5P · 7m | C E♭ G B♭ |
| Half-diminished | Cm7b5 | 1P · 3m · 5d · 7m | C E♭ G♭ B♭ |
| Diminished seventh | Cdim7 | 1P · 3m · 5d · 7d | C E♭ G♭ B𝄫 |
| Minor/major seventh | CmMaj7 | 1P · 3m · 5P · 7M | C E♭ G B |
| Add nine | Cadd9 | 1P · 3M · 5P · 9M | C E G D |
| Dominant ninth | C9 | 1P · 3M · 5P · 7m · 9M | C E G B♭ D |
| Major ninth | Cmaj9 | 1P · 3M · 5P · 7M · 9M | C E G B D |
| Minor ninth | Cm9 | 1P · 3m · 5P · 7m · 9M | C E♭ G B♭ D |
| Dominant thirteenth | C13 | 1P · 3M · 5P · 7m · 9M · 13M | C E G B♭ D A |
Questions
- How does the chord identifier name a chord?
- It reduces your notes to pitch classes, takes the lowest as the bass, and compares the set against every chord type it knows, a hundred and six of them, from a major triad to a thirteenth with an altered eleventh. Every type whose notes match exactly is offered; the most familiar name in root position comes first, and the readings that need a slash come after it.
- Why do the same notes get several names?
- Because chords share notes. C E G A is C6 with the root at the bottom and Am7/C read from A; A C E♭ G♭ is a diminished seventh whichever note you start on. The name that fits the bass and the most common chord type is shown first; the others are listed so you can pick the one your chart or your ear prefers.
- What is an inversion, and what does the slash mean?
- An inversion is the same chord with a note other than the root at the bottom: first inversion has the third in the bass, second the fifth, third the seventh. Charts write it as a slash chord, C/E, meaning a C chord over an E. The tool names the inversion and shows the slash symbol whenever the lowest note is not the root.
- Why does it write B♭ rather than A♯?
- They are the same key, but a chord is spelled in thirds, and a name that skips or doubles a letter reads badly: A♯ major would be A♯ C𝄪 E𝄪. The tool tries both spellings and keeps the one with the fewest accidentals, leaving a tie the way you typed it. The ♯ and ♭ toggles force one spelling when a chart needs it.
- What if I only have two notes?
- Two notes make an interval, not a chord, and the tool says which one — a major third, a perfect fifth — with a link to that interval’s page. A root and a fifth is also a power chord, written C5, and that name is offered too. For its inversion and size in cents, work out the interval between the two notes.
- Why does it say Dm7 when I never played an A?
- Because players leave the fifth out all the time: it adds nothing to the quality of a chord, so a pianist’s left hand or a guitarist’s voicing often drops it. The tool assumes a perfect fifth by default, so D F C is named Dm7. A toggle appears whenever that assumption changes the answer, and turning it off names only what you actually played.
- Does it work for guitar, piano or any instrument?
- Yes. A chord is its notes, whatever instrument they are played on. Tap them on the keyboard here, or type them — letters or Do Ré Mi, with or without octaves — and the result plays on the instrument chosen in the playback bar: piano, guitar, ukulele or bass.
- Is it free, and where do my notes go?
- It is free and needs no account. Everything happens in your browser: nothing you play or type is sent to a server or stored anywhere but in the address bar, which is what lets you share or bookmark a result.