Theory

Triad Sharing

Build a progression and see each chord's triad tones on one fretboard, colour-coded per chord, with shared frets as pie-slice dots.

Guitar
Ukulele
Banjo
Bass

Triad Sharing on guitar, the Triads tab, with only C (blue) switched on and only the 123 string-set box ticked; 234, 345 and 456 are unticked. The fretboard from fret 4 shows the notes C, E and G as blue dots on the top three strings only (high E, B and G); the lower three strings are empty.

One string set: with only 123 ticked, C’s triad appears on the top three strings alone.

Triad Sharing on guitar, the Triads tab, with five chords listed (C, Am, F, G and Em) and only C (blue) switched on. The string-set boxes 123, 234, 345 and 456 are all ticked. The fretboard from fret 4 shows just the notes C, E and G, all as solid blue dots.

One chord on its own: the C, E and G of a C triad across the neck.

Triad Sharing on guitar, the Triads tab, with five chords listed: C (blue) and Am (green) switched on, F, G and Em switched off. The string-set boxes 123, 234, 345 and 456 are all ticked. The fretboard from fret 4 shows the notes of each triad, with the notes C and E shared by both chords as blue and green pie-slice dots.

C and Am: they share C and E, so those dots are split blue and green.

Triad Sharing on guitar with Em (orange) switched on alongside C and Am. Dots shared between chords are split into pie slices, and B, the one note only Em has, appears as a solid orange dot.

Add Em: it shares E and G with the others, and only B is new.

Triad Sharing on guitar with C (blue), Am (green), G (purple) and Em (orange) switched on and F switched off. D, the one note only G has, appears as a solid purple dot; the rest are pie slices of two or three colours.

Four chords of a progression at once, with D the only note unique to G.

Triad Sharing on ukulele, the Triads tab, with only C (blue) switched on and only the 123 string-set box ticked; 234 is unticked. The fretboard shows the notes C, E and G as blue dots on the top three strings only (A, E and C); the G string is empty.

One string set: with only 123 ticked, C’s triad appears on the top three strings alone.

Triad Sharing on ukulele, the Triads tab, with five chords listed (C, Am, F, G and Em) and only C (blue) switched on. Both string-set boxes, 123 and 234, are ticked. The fretboard shows just the notes C, E and G as solid blue dots, now on all four strings (A, E, C and G).

One chord on its own: the C, E and G of a C triad across all four strings.

Triad Sharing on ukulele with C (blue) and Am (green) switched on, F, G and Em switched off. Both string-set boxes are ticked. The notes C and E, shared by both chords, are dots split into blue and green pie slices; the A of Am is a solid green dot and the G of C a solid blue dot.

C and Am: they share C and E, so those dots are split blue and green.

Triad Sharing on ukulele with Em (orange) switched on alongside C and Am. Dots shared between chords are split into pie slices, and B, the one note only Em has, appears as a solid orange dot.

Add Em: it shares E and G with the others, and only B is new.

Triad Sharing on ukulele with C (blue), Am (green), G (purple) and Em (orange) switched on and F switched off. D, the one note only G has, appears as a solid purple dot; the rest are pie slices of two or three colours.

Four chords of a progression at once, with D the only note unique to G.

Triad Sharing on banjo in Open G, the Triads tab, with only C (blue) switched on and only the 123 string-set box ticked; 234 is unticked. The fretboard shows the notes C, E and G as blue dots on the D, B and G strings and the short g string; the lower D string is empty.

One string set: with only 123 ticked, the lower D string is left empty.

Triad Sharing on banjo in Open G, the Triads tab, with five chords listed (C, Am, F, G and Em) and only C (blue) switched on. Both string-set boxes, 123 and 234, are ticked. The fretboard shows just the notes C, E and G as solid blue dots, now including the lower D string. The short g string starts at the 5th fret.

One chord on its own: the C, E and G of a C triad across the neck.

Triad Sharing on banjo with C (blue) and Am (green) switched on, F, G and Em switched off. Both string-set boxes are ticked. The notes C and E, shared by both chords, are dots split into blue and green pie slices; the A of Am is a solid green dot and the G of C a solid blue dot.

C and Am: they share C and E, so those dots are split blue and green.

Triad Sharing on banjo with Em (orange) switched on alongside C and Am. Dots shared between chords are split into pie slices, and B, the one note only Em has, appears as a solid orange dot.

Add Em: it shares E and G with the others, and only B is new.

Triad Sharing on banjo with C (blue), Am (green), G (purple) and Em (orange) switched on and F switched off. D, the one note only G has, appears as a solid purple dot, including on the open D strings; the rest are pie slices of two or three colours.

Four chords of a progression at once, with D the only note unique to G.

Triad Sharing on bass, the Triads tab, with only C (blue) switched on and only the 123 string-set box ticked; 234 is unticked. The fretboard from fret 4 shows the notes C, E and G as blue dots on the top three strings only (G, D and A); the E string is empty.

One string set: with only 123 ticked, C’s triad appears on the G, D and A strings alone.

Triad Sharing on bass, the Triads tab, with five chords listed (C, Am, F, G and Em) and only C (blue) switched on. Both string-set boxes, 123 and 234, are ticked. The fretboard from fret 4 shows just the notes C, E and G as solid blue dots on all four strings (G, D, A and E).

One chord on its own: the C, E and G of a C triad across the neck.

Triad Sharing on bass with C (blue) and Am (green) switched on, F, G and Em switched off. Both string-set boxes are ticked. The notes C and E, shared by both chords, are blue and green pie-slice dots; A, which only Am has, is a solid green dot.

C and Am: they share C and E, so those dots are split blue and green.

Triad Sharing on bass with Em (orange) switched on alongside C and Am. Dots shared between chords are split into pie slices, and B, the one note only Em has, appears as a solid orange dot.

Add Em: it shares E and G with the others, and only B is new.

Triad Sharing on bass with C (blue), Am (green), G (purple) and Em (orange) switched on and F switched off. D, the one note only G has, appears as a solid purple dot; the rest are pie slices of two or three colours.

Four chords of a progression at once, with D the only note unique to G.

Triad Sharing is the Triads tab of Scales. It does for triads what Scale Sharing does for scales: it shows where chords overlap on the neck.

Use the instrument tabs above the screenshots to see it on guitar, ukulele, banjo or bass; the strings and tuning follow the instrument.

How it works

Build a progression and see each chord’s triad tones across the fretboard, colour-coded per chord. Where two or more chords share a fret, the dot is split into pie slices, one per chord.

String sets

Under the Root and Type pickers are checkboxes such as 123 and 234. Each is a string set, three adjacent strings, numbered from string 1 (the highest-pitched). On guitar there are four sets (123, 234, 345 and 456); on ukulele, banjo and bass the app offers two, 123 and 234. With every box ticked, the triad tones are shown across the whole neck.

Tick only the set you want and the fretboard shows the triad tones on just those three strings, which is how a triad is usually played.

Learning a chord on one string set

Ticking one string set turns the fretboard into a map of a single chord’s triad on those three strings:

Tick one string set, say 234, and show one chord at a time, using the eye to hide the others.
Find that chord’s triad tones along the three strings. They repeat up the neck, so the same chord can be played in several places within a few frets of each other.
Learn where they sit until you can find them without looking.
Switch on the next chord in the progression. Where the two chords share a fret, the dot is split into pie slices, so you can see which notes stay put and which move.

Do this for each chord in a key and you have its triads on one set of strings, all within the same few frets. That’s what lets you improvise around a key: when the chord changes, you move the shortest distance to the next chord’s tones and your solo follows the harmony. Then repeat on another string set to get the same chords in a different part of the neck.

Ideas to try

Find the overlaps – look for frets shared by neighbouring chords in a progression, so you can move between them with the least hand movement.