Chord Builder & Inverter

Runs entirely in your browser — no audio or data ever leaves your device (see methodology).

How It Works

This tool builds a chord from two choices — a root and a quality — and then does the thing a static chord diagram cannot: it shows you the same chord with each of its notes taken in turn as the lowest one, which is what an inversion actually is. Thirty-four qualities are available, running from a two-note power chord through the ordinary triads and sevenths to altered dominants with a flattened ninth or a sharpened eleventh, and every one of them is generated from its real interval formula rather than looked up in a table of shapes. The inversion display is the part worth understanding before you use it. An inversion is not a different set of notes and it is not a re-ordering of a list; it is the same chord with a different note at the bottom, and that distinction only becomes visible when the notes are drawn at their real pitches rather than folded into a single octave. A C major chord and a C major chord with E in the bass contain identical pitch classes, so any diagram that highlights pitch classes draws them as the same picture. The keyboards here span three octaves and show actual notes, so each inversion looks like what it is: the bottom note has moved up an octave and everything else has stayed put. That also answers the question that brings most people here. A third inversion requires a fourth note, because there have to be four chord tones before a fourth of them can go in the bass. A triad has three positions in total — root position, first inversion and second inversion — and no third inversion exists for it at all. A seventh chord is the smallest chord that has one, and in a seventh chord the third inversion puts the seventh itself at the bottom, which is why it sounds so unstable and why it almost always resolves downward by step. Each inversion is labelled three ways: by its ordinary name, by its slash-chord name in the form guitarists and lead sheets use, and by its figured-bass figure where classical practice defines one. Above a seventh chord no standard figure exists, and rather than inventing one the tool says so and names those positions by which note is in the bass. Extended chords get the same treatment and an honest note about what happens to them in practice. A thirteenth chord contains six notes in theory: root, third, fifth, seventh, ninth and thirteenth. A guitar has six strings and a hand has four usable fingers, and a pianist voicing the same chord in one hand has five. Real players therefore drop notes, and they drop them in a consistent order — the fifth goes first because it contributes least, then the root if a bass player is covering it, and on an eleventh chord the third often goes too because a natural eleventh sits a semitone above it and grinds. Every note the tool shows is genuinely part of the chord; the subset you actually finger is a separate decision, and the page says which notes are usually the ones to lose. Note spelling is done by chord degree rather than by pitch, which is why the results look like written music rather than like a list of nearest names. A C seven sharp nine is spelled C, E, G, B flat, D sharp — the sharpened ninth is a ninth, so it has to be some kind of D, even though the same pitch could be called E flat. A C diminished seventh needs a double flat, because its seventh degree has to be some kind of B and the pitch required is two semitones below B natural. Getting this right is not pedantry: a chord symbol tells you which degrees are present and which are altered, and a spelling that renames a sharpened ninth as a flattened third describes a different chord. Underneath the inversion grid, the selected inversion is mapped across a whole fretboard — guitar, ukulele or bass — with every position of every chord tone labelled by degree, the root in one colour and the bass note in another. This is deliberately a different picture from the chord diagrams on this site's individual chord pages, which show one specific fingering. Here you get the raw material instead: everywhere the chord's notes live on the neck, so you can build your own voicing with the required bass note at the bottom rather than memorising someone else's shape. Everything computes in the browser and plays through the browser's own audio, generated from an oscillator rather than from any sound file, so nothing is downloaded and nothing you select is sent anywhere. The root, quality and selected inversion are all written into the address bar, which makes any chord in any inversion a link you can send to someone.

FAQ

Why does a triad have no third inversion?

Because an inversion is named for which chord tone is in the bass, and a triad only has three tones. Root position, first inversion and second inversion use all of them. A third inversion needs a fourth note, which is why the smallest chord that has one is a seventh chord.

What is the difference between an add9 chord and a 9th chord?

The seventh. A ninth chord is a seventh chord continued up another third, so it contains root, third, fifth, seventh and ninth. An add9 chord adds the ninth to a plain triad and leaves the seventh out entirely, which is a noticeably more open sound.

Do I have to play every note of an 11th or 13th chord?

No, and almost nobody does. Six-note chords do not fit comfortably on six strings or under one hand. The fifth is dropped first, the root next if a bass is covering it, and on an eleventh chord the third is often dropped because it clashes with the natural eleventh.

Why is the ♯9 written as a D sharp rather than an E flat?

Because it is a ninth, and a ninth has to be some kind of second-letter-above-the-root. In a C chord that letter is D, so a raised ninth is D sharp. Calling it E flat would name it as a third instead, which describes a different chord.