Built by stacking thirds inside the scale itself — take every other note starting from each degree. Nothing is looked up, which is why it works for the modes and the harmonic minor as well as for the major. Each one links through to the chord shapes.
A mode is not a new set of notes — it is the same set with a different note treated as home. D dorian and C major contain exactly the same seven pitches; what differs is which one the music keeps returning to.
A scale is a list of distances from its root, in semitones. Major is 0 2 4 5 7 9 11. A guitar is six strings whose open pitches you know. Everything on this page — which frets light up, which chords fit, which mode you are actually in, where your hand can sit — follows from those two lists and nothing else. There is no table of shapes, which is why changing the tuning or the capo does not break anything.
Getting the pitches right is easy: add the interval to the root and take it modulo twelve. Getting the names right is not, and it is the difference between a diagram and a piece of music notation.
A seven-note scale uses each letter exactly once — that is what makes it readable on a stave, because each line and space is used once and the accidentals do the rest. So the page assigns the letters first, A to G in order from the root, and then asks what accidental each one needs to land on the required pitch. F♯ major therefore contains E♯, not F, even though those are the same fret: calling it F would mean using the letter F twice and the letter E not at all. Follow the rule far enough and it produces double sharps — G♯ major genuinely contains an F𝄪 — at which point the page says so rather than quietly rounding it off to G.
Scales with five, six or eight notes cannot obey that rule, because there are not seven letters to go round. Those are spelled by pitch instead, and labelled as such.
The five familiar shapes are usually presented as things to memorise. They are not arbitrary: a position is a window the width of one hand that contains at least two of the scale's notes on every string, so a phrase can be played inside it without shifting. Ask the neck that question directly and the shapes fall out, in the right places, for any scale and any tuning. Change the tuning to DADGAD and you get the DADGAD positions, which no table would have had.
Two details had to be got right before that worked. A window that merely fits is not a position — for a seven-note scale every fret fits, so the first attempt found one position where there are seven. What separates them is where the hand starts: the first finger on a scale note on the lowest string, which gives one position per note in the scale and matches what players call first, second and third position.
And the hand is not always four frets. Four is enough for any seven-note scale, but a pentatonic spreads five notes over twelve semitones and the familiar boxes genuinely need a one-fret stretch — asking for four returned three boxes for A minor pentatonic and five for C minor pentatonic, which is the same scale twice. The search now widens until it finds a position for every note in the scale, and the caption under the neck says which reach it used.
Only which note the music treats as home. Play the same seven pitches over a C bass and it is C major; play them over a D bass and the ear hears D as the centre, which puts a minor third and a major sixth above it and produces the dorian sound. That is why the drone on this page matters more than the diagram: the notes do not change, the gravity does.
Because it is. Removing two notes from the major scale takes out both of the semitone steps, which are the intervals most likely to clash with whatever chord is underneath. What is left is two notes per string in every position, evenly spread, and nothing that sounds obviously wrong. That is the whole reason it is the first scale most guitarists learn, and the reason it stops being interesting later.
The flattened fifth added to the minor pentatonic is a passing note, not a resting one — it belongs between the fourth and the fifth and sounds wrong if you stop on it. It is also an approximation: the pitch it stands in for is not on the fretboard at all, which is why the blues is bent rather than fretted.
They do not, quite — the set of chords stays the same, because the notes do. What changes is which one is the tonic and therefore how the others function. The same six chords that make C major sound like C major make A minor sound like A minor; the vi becomes the i, and the whole thing reorients around it.
Both, and in that order, is the honest answer. The boxes let you play something today; the note names let you know what you played. Switching the labels between note names and scale degrees on the same diagram is a cheap way to start joining the two together, which is why the toggle is there rather than a preference buried in a menu.
Twelve-tone equal temperament, and that your instrument is in tune with itself. The spelling rules are those of Western common-practice notation; other traditions name these intervals differently and some do not use twelve of them. The position search assumes a four-fret reach, which is a fair description of most hands in the middle of the neck and an optimistic one at the first fret.
This page has changed in 2 archived releases, but each of those was a site-wide pass, so none is attributable to this tool on its own and none is listed here. That is not a claim that the tool never changed — a release that reworked many pages at once may well have altered this one too. The changelog has them.