GressusPiano · Reference

How to Build a Chord on Piano

Fig. 1 — the chord library

Choose the root (the note a chord is named after), then its quality and variant. Every diagram in this book is this same card: the tool and the textbook are one and the same.

Most people learn chords as hand positions. You are shown where the fingers go, you copy it, and after enough repetition the shape arrives without being asked. It works — and it stops working the moment someone writes Cmaj7 or F♯ø7 and there is no diagram underneath.

Chords are not arbitrary shapes. Every one is built from the same small set of rules, and on a keyboard those rules are unusually easy to see: the keys are evenly spaced, so the distance between two notes is something you can literally count.

What follows sets out those rules in full: the distances and their names, the families they build, and the way one set of notes can be re-stacked to sit differently under the hand. None of it requires you to read music, and none of it has to be memorised — it has to be counted.

The library on the facing page is the tool used throughout. Every diagram you meet below is one of its cards, so nothing in this book is an illustration of the thing; it is the thing.

Open the whole chord library Practise free with Gressus

How to Build a Chord01

GressusThe library

Fig. 1 — the chord library

Full screen

Pick a letter, a quality and a variant. Every diagram in this book is this same card — the tool and the textbook are one and the same.

Practise free with Gressus

How to Build a Chord02

GressusFoundations

What a chord is

A chord is three or more notes sounded together. What makes it that particular chord is not which notes it contains in the abstract — it is the distances between them. A major chord built on C and a major chord built on F♯ share no notes at all, but they are the same chord type because the distances inside them are identical.

Chords are patterns of distance, not lists of notes.

Every chord is described relative to its root — the note the chord is named after. In a G major chord, G is the root. Everything else is measured from there.

Counting in keys

A semitone is the smallest step in music, and on a keyboard it is simply the very next key — counting the black ones. From C to the black key above it is one semitone. From C to D is two, because you passed a black key on the way.

Fig. 2 — counting keys

One semitone

Two semitones

This is the piano's great advantage for learning chords. The keys are evenly spaced, so a distance you can count is a distance you can see. Number the root 0, then count keys upwards, and every chord in music becomes arithmetic.

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GressusIntervals

The named distances

Each distance has a name and a shorthand. The shorthand — R, ♭3, 5 — is the degree: what the interval is called relative to the root. These labels are used throughout this book and on the library.

Table 1 · The intervals within one octave

Keys	Interval	Degree
0	Root (unison)	R
1	Minor second	♭2
2	Major second	2
3	Minor third	♭3
4	Major third	3
5	Perfect fourth	4
6	Tritone (dim fifth)	♭5
7	Perfect fifth	5
8	Minor sixth (aug fifth)	♭6 / ♯5
9	Major sixth	6
10	Minor seventh	♭7
11	Major seventh	7
12	Octave	R

The root is marked in gold throughout, as it is everywhere else in Gressus — on the wheel, on the key picker, wherever a tonic is shown. Of the rest, only a handful do the heavy lifting: the third decides whether a chord sounds major or minor, the fifth makes it sound stable, and the seventh gives it flavour and pull. Almost everything else is decoration.

One degree is greyed out. The ♭2 is the only distance in the octave that appears in none of the twelve chord types in this book — every other one belongs to at least one of them. That is not the same as useless: it is everywhere as a passing note, and it does turn up in richer chords than these pages cover. It simply never forms part of a chord you would be asked to hold.

Eight keys is a minor sixth in a scale; in a chord it is usually the raised fifth of an augmented triad, which is why the chord pages write it ♯5.

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GressusThe triad

The major triad

A triad is a three-note chord, and the major triad is the one everything else is measured against.

Major0 · 4 · 7

Start on the root. Count four keys up — black keys included — for the major third. Count seven up from the root for the perfect fifth. In degrees:

R·3·5

Fig. 3 — C major, counted out

C, then four keys up to E, then three more to G. The coloured keys are the chord; the white gaps between them are the intervals.

Built on D that gives D, F♯, A. Built on B♭: B♭, D, F. The same two steps every time — four then three — only the starting key moves.

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GressusMajor & minor

One key apart

Move the middle note down by a single key — from four steps to three — and the chord becomes minor. That one key is the entire difference between the two most common chords in music.

Fig. 4 — the same chord, one key moved

E♭

C major and C minor. The outer two keys are identical. Only the middle one has shifted down — E becomes E♭.

The root is unchanged. The fifth is unchanged. Only the middle note moves. The third carries the mood.

Everything else on this page is that same procedure with different numbers. Once you can hear one key move, you can hear all of them.

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GressusChord by chord

The minor triad

Minor0 · 3 · 7

R·♭3·5

Three keys up for the minor third, then four more for the fifth. Note what happened: the major triad is four-then-three, the minor is three-then-four. The same two steps, swapped over.

Fig. 5 — built on C

E♭

C, three keys up to E♭, four more to G.

As common as major, and the whole difference is one key in the middle. Pop, folk, rock, classical — everywhere.

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GressusSuspended

Taking the third away

Everything so far has moved the third or the fifth. A suspended chord does something different: it removes the third altogether and puts a neighbouring note in its place — the second below it, or the fourth above.

Because the third is the note that decides major or minor, a chord without one is neither. That is the whole character of these chords, and it is why they sit here beside major and minor rather than with the diminished and augmented chords overleaf: a sus chord is a further deviation of the third, not a change to the fifth. The fifth never moves.

Fig. 6 — the third, replaced from either side

Csus2 and Csus4. The outer notes are a plain C and G in both; only the middle key has moved off the third, down to D or up to F.

Table 2 · The suspended chords

Chord	Degrees	Keys	On C
Sus2	R 2 5	0 2 7	C D G
Sus4	R 4 5	0 5 7	C F G

They sound like they are waiting for something, and usually they are: a sus4 most often resolves by dropping the fourth onto the third a moment later. That is where the name comes from — the note is suspended before it lands.

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GressusChord by chord

The suspended second

Sus20 · 2 · 7

R·2·5

Two keys up, then five more. There is no third at all — the note that would decide major or minor is replaced by the one below it.

Fig. 7 — built on C

C, D, G. The second sits where the third would be.

Neither major nor minor, so it sounds open and unfinished in an agreeable way. Pop, folk and rock lean on it for colour and movement.

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GressusChord by chord

The suspended fourth

Sus40 · 5 · 7

R·4·5

Five keys up, then two more. Again no third — this time replaced by the note above it.

Fig. 8 — built on C

C, F, G. The fourth sits where the third would be.

The classic delay: a sus4 usually resolves by dropping the fourth onto the third a moment later. That is where the name comes from — the note is suspended before it lands.

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GressusThe triad family

Now move the fifth

Put the third back, and turn to the note above it. Lower the fifth and the chord becomes diminished; raise it and the chord becomes augmented.

Fig. 9 — the four triads on C

E♭

G♭

G♯

Major, minor, diminished, augmented — all rooted on C. Watch the upper two keys walk down, then up.

Table 3 · The triads

Chord	Degrees	Keys	On C
Major	R 3 5	0 4 7	C E G
Minor	R ♭3 5	0 3 7	C E♭ G
Diminished	R ♭3 ♭5	0 3 6	C E♭ G♭
Augmented	R 3 ♯5	0 4 8	C E G♯

Diminished takes the minor triad and pulls the fifth down as well, so both upper notes are lowered — which is why it sounds tense and unable to settle. Augmented does the opposite to the major triad and pushes the fifth up. Both are built from two equal steps. Augmented goes further: its two major thirds and the gap back to the octave are all four keys, so it divides the octave exactly into three, and that symmetry is what makes it sound rootless.

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GressusChord by chord

The diminished triad

Dim0 · 3 · 6

R·♭3·♭5

Three keys, then three more. Two identical minor thirds stacked on top of each other.

Fig. 10 — built on C

E♭

G♭

C, E♭, G♭ — evenly spaced, which is why it sounds unable to settle.

Tense and unresolved, so it is nearly always passing through on its way somewhere. Common in classical harmony and in jazz; rare as a resting place.

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GressusChord by chord

The augmented triad

Aug0 · 4 · 8

R·3·♯5

Four keys, then four more. Two identical major thirds, with the fifth pushed up rather than pulled down.

Fig. 11 — built on C

G♯

C, E, G♯ — evenly spaced again, but wider.

Because its steps are equal it divides the octave into three, so only four augmented triads exist in all and each one belongs to three roots at once. Used as a link between chords in classical and jazz writing.

How to Build a Chord13

GressusSevenths

Adding a fourth note

Stack one more note on a triad and you get a seventh chord. The note added is usually ten keys above the root (♭7) or eleven (7); in the diminished seventh and the sixth it is nine — and which one, on top of which triad, gives each seventh chord its character.

Table 4 · The seventh chords

Chord	Degrees	Keys	On C
Dominant 7	R 3 5 ♭7	0 4 7 10	C E G B♭
Major 7	R 3 5 7	0 4 7 11	C E G B
Minor 7	R ♭3 5 ♭7	0 3 7 10	C E♭ G B♭
Half-diminished 7	R ♭3 ♭5 ♭7	0 3 6 10	C E♭ G♭ B♭
Diminished 7	R ♭3 ♭5 ♭♭7	0 3 6 9	C E♭ G♭ A
Sixth	R 3 5 6	0 4 7 9	C E G A

The sixth is the odd one in that list — its extra note sits a step below the seventh rather than on it, and it stays bright and resolved where the sevenths pull. It is grouped here because it is built the same way: a complete triad, plus one.

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GressusSevenths

Two pairs worth knowing

Fig. 12 — one key, two very different chords

B♭

C7 and Cmaj7. The top note differs by a single key — and C7 pulls hard towards F while Cmaj7 does not pull anywhere at all.

That is the page's first idea arriving again: one key changes everything. It was true of the third, and it is just as true four notes in.

The two diminished sevenths

Both are built on a diminished triad, and they too differ by a single key at the top. The half-diminished takes an ordinary minor seventh; the fully diminished pulls that seventh down one more key. That is where the name comes from: it is only half of the way to being fully diminished.

Half-diminished is written ø7 — it is the viiø7 of a major key and the iiø7 of a minor one, which is why it is everywhere in Bach, Mozart and Beethoven. Fully diminished is °7, and its top note is written as a doubly-flattened seventh: on C that would be B♭♭, which sounds identical to A. Most editions — this library included — print the easier name. The odd spelling survives because of the job the chord does, not because it sounds like anything else.

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GressusChord by chord

The dominant seventh

Dom70 · 4 · 7 · 10

R·3·5·♭7

A major triad, then a minor seventh — ten keys above the root, two below the octave.

Fig. 13 — built on C

B♭

C, E, G, B♭.

Restless: it wants to move, and where it wants to move is a fourth up. That pull is the engine of the blues and of most traditional harmony.

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GressusChord by chord

The major seventh

Maj70 · 4 · 7 · 11

R·3·5·7

A major triad, then a major seventh — eleven keys up, the key immediately below the octave.

Fig. 14 — built on C

C, E, G, B. One key higher on top than C7, and a different world.

Open, warm and settled — it pulls nowhere at all. Jazz, soul, bossa nova and ballads are built on it.

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GressusChord by chord

The minor seventh

Min70 · 3 · 7 · 10

R·♭3·5·♭7

A minor triad, then a minor seventh on top.

Fig. 15 — built on C

E♭

B♭

C, E♭, G, B♭.

Soft and unhurried, with none of the dominant seventh's urgency. The workhorse chord of jazz, soul and funk.

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GressusChord by chord

The half-diminished seventh

Half-dim0 · 3 · 6 · 10

R·♭3·♭5·♭7

A diminished triad, then an ordinary minor seventh — not a diminished one. That single choice is what makes it half diminished.

Fig. 16 — built on C

E♭

G♭

B♭

C, E♭, G♭, B♭. Written Cø7.

Core classical harmony, not a jazz import: it is the viiø7 of a major key and the iiø7 of a minor one, which puts it throughout Bach, Mozart and Beethoven. The Tristan chord is usually read as one.

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GressusChord by chord

The diminished seventh

Dim70 · 3 · 6 · 9

R·♭3·♭5·♭♭7

A diminished triad, then three more keys. Every step is three keys — the most evenly spaced chord in music.

Fig. 17 — built on C

E♭

G♭

C, E♭, G♭, and a top note written B♭♭ but printed here, as in most editions, by its easier name.

Maximally unstable, and perfectly symmetrical: it divides the octave into four, so only three exist and each belongs to four roots at once. That ambiguity makes it the great pivot chord of classical and jazz writing.

How to Build a Chord20

GressusChord by chord

The sixth

6th0 · 4 · 7 · 9

R·3·5·6

A complete major triad, then two more keys above the fifth for the sixth.

Fig. 18 — built on C

C, E, G, A — a major chord with one extra note on top.

Bright and fully resolved, unlike the sevenths. For decades it was the default way to end a song: jazz, swing and older pop.

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GressusInversions

The same notes, reordered

Nothing says the root has to be at the bottom. Take the lowest note of a chord and move it up an octave and you have the same chord — the same three notes, the same name — sitting differently under the hand. This is an inversion.

Fig. 19 — C major, three ways

Root position, first inversion, second inversion. Every one of them is C major — C, E and G throughout. Only the lowest note has changed.

When the root is not the lowest note the chord is written with a slash: C/E is C major with E in the bass, C/G with G in the bass. The letter after the slash is simply whichever note ended up at the bottom.

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GressusInversions

Four notes, four positions

A seventh chord has one more note than a triad, so there is one more place the bass can be. The rule does not change — take the lowest note and move it up an octave — it simply happens once more.

Fig. 20 — C7, four ways

B♭

Every one of them is C7 — C, E, G and B♭ throughout. Only the lowest note changes: C, then E, then G, then B♭.

Written out, that is C7, C7/E, C7/G and C7/B♭. The letter after the slash is simply whichever note ended up at the bottom, exactly as with a triad.

The last one is worth knowing by name. Third inversion puts the seventh in the bass — the note that most wants to fall — so it is the least settled of the four, and it almost always resolves by stepping down.

How to Build a Chord23

GressusWhy they matter

Why bother inverting

Your hand stops jumping

Playing C then F in root position throws the hand across the keyboard. Play C, then F in second inversion, and most of your fingers barely move. Inversions are what make chord changes smooth rather than athletic.

The bass line becomes a line

Choosing which note sits at the bottom lets the lowest voice step rather than leap. That is why slash chords appear so often in written music — they are usually there to make the bass move by one step.

The chord changes character

Same notes, different weight. Root position sounds settled and final; an inversion sounds lighter, more in transit. Useful when you want a chord to lead somewhere instead of stopping.

A triad has three notes, so it has three positions: root, first, second. A seventh chord has four, so it has four.

You will find that the library ignores the inversions a chord does not have. Suspended and augmented chords are left in root position throughout — a deliberate choice, because inverting them produces a chord that is more usefully named as something else entirely.

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GressusIn practice

Putting it to work

Building a chord you have never played

Take the root, apply the formula, count the keys. F♯ø7 is R ♭3 ♭5 ♭7 from F♯: three keys up, then three more, then four more — F♯, A, C, E. You did not need a chord dictionary; you needed to count to twelve.

Transposing

If a song sits too high to sing, the pattern of distances is what stays fixed while everything else moves. Shift every root by the same number of keys and the song is intact in a new key.

Reading a chord symbol

A symbol is a set of instructions, not a name to look up. Cmaj7 is "C, plus four keys, plus three more, plus four more". Read symbols that way and an unfamiliar chord stops being an obstacle.

Practising deliberately

Build the same chord type on several different roots, rather than several different chords on one root. It is the pattern you are learning, not the hand position.

How to Build a Chord25

GressusCommon questions

Common questions

Do I count black keys?

Yes — always. A semitone is the very next key of any colour. Forgetting the black keys is the single most common counting error.

Why is C♯ sometimes called D♭?

They are the same key on a piano, spelled differently depending on the music around them — two names for one pitch are called enharmonic equivalents . The library follows whichever spelling suits the chord, which is why you will sometimes see G♭ rather than F♯ inside the same diagram.

Which fingers should I use?

For a root-position triad in the right hand, 1‑3‑5 is the usual starting point. Fingering is a separate subject from construction, and it changes with inversions and with what comes next.

Do I have to play all the notes?

No. The third and the seventh identify a chord; the fifth is the least informative note and is routinely dropped. What you should not drop is the third, unless you mean to — without it the chord is no longer major or minor.

Some books write ø7 and others write m7♭5 — which is right?

Both name the same four notes. ø7 — half-diminished seventh — is the standard name in classical theory and the one used here. m7♭5 is the jazz and lead-sheet spelling, which describes the chord by how it is altered rather than by what it is. Expect to meet both.

What is the difference between C7, Cmaj7 and Cm7?

The triad underneath and the seventh on top. C7 is major with a flattened seventh; Cmaj7 is major with a natural seventh; Cm7 is minor with a flattened seventh.

Why do sus chords sound unfinished?

They have no third, so they are neither major nor minor. The ear waits for the third to arrive.

Is C/E a different chord from C?

No — the same three notes, with E at the bottom instead of C. It is C major in first inversion.

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TOM · Teacher Of Music

The old textbook, brought to life.

Every diagram here is a tool you actually use — free, and built to practise with.

Practise free with Gressus