How does the tool identify a chord?

It reduces your notes to their pitch classes (ignoring octave), then tries each note as a possible root and compares the resulting interval set against a library of chord shapes — triads, sixths, sevenths and common extensions. The first exact match gives the root and quality.

How are inversions and slash chords detected?

Once the root is found, the tool checks whether the lowest note you entered equals that root. If the bass differs, the chord is an inversion and is written as a slash chord, such as C/E for a C major triad with E in the bass.

What note formats are accepted?

Enter letter names A to G with optional sharps (#) or flats (b), separated by spaces or commas. Octave numbers are ignored, so C, C3 and C5 are treated the same. Enharmonic spellings like C# and Db are both understood.

Why does it say no chord matched?

The note set may not correspond to a standard chord in the library, or it may contain only one unique pitch class. The interval list from the bass is still shown so you can inspect the relationships, even when no named chord fits — useful for clusters and non-tertian voicings.

What do the interval names mean?

Each interval is the distance in semitones from the bass note, named by its musical quality: 4 semitones is a major 3rd, 7 a perfect 5th, 10 a minor 7th, and so on. These show how the voicing is built and help you spot the chord's character at a glance.

What is the Chord Interval Finder?

Free chord interval finder. Enter a set of notes to identify the chord name, root, quality and every interval relationship, including inversions and slash chords. Handles triads, seventh chords and extensions. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Chord Interval Finder

Name: Chord Interval Finder
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Play a handful of notes and want to know what chord they form? This finder takes a set of notes, identifies the chord name, root and quality, flags any inversion as a slash chord, and lists every interval measured from the bass — so you understand both the label and the structure.

How it works

The tool first converts your notes into pitch classes (0 to 11, where C is 0), removing duplicate octaves. To name the chord it treats each note in turn as a candidate root and measures the intervals of the other notes relative to it:

relative interval = (note pitch class − root pitch class + 12) mod 12

The resulting sorted interval set is compared against a library of chord templates — major and minor triads, diminished, augmented, sus2/sus4, sixths, and the seventh-chord family (maj7, 7, m7, m7b5, dim7 and more). When an exact match is found, that note is the root and the template gives the quality.

If the lowest note you entered is not the root, the chord is an inversion, written as a slash chord like G/B. The interval list is always measured from the bass note so you can see exactly how the voicing is stacked.

Interval reference — semitones to musical names

Semitones	Interval name	Abbreviation
0	Unison / Octave	P1 / P8
1	Minor 2nd	m2
2	Major 2nd	M2
3	Minor 3rd	m3
4	Major 3rd	M3
5	Perfect 4th	P4
6	Tritone (aug 4th / dim 5th)	TT
7	Perfect 5th	P5
8	Minor 6th	m6
9	Major 6th	M6
10	Minor 7th (dominant 7th)	m7
11	Major 7th	M7

Chord shapes the tool recognises

The library covers the chords used in the vast majority of Western tonal music:

Triads: major (M3, P5), minor (m3, P5), diminished (m3, dim5), augmented (M3, aug5)
Suspended: sus2 (M2, P5), sus4 (P4, P5)
Added sixth: major 6 (M3, P5, M6), minor 6 (m3, P5, M6)
Seventh chords: dom7 (M3, P5, m7), maj7 (M3, P5, M7), m7 (m3, P5, m7), m(maj7) (m3, P5, M7), m7b5 (m3, dim5, m7), dim7 (m3, dim5, dim7)

When notes are entered that do not match any template, the tool shows the interval list from the bass without a chord name — useful for analysing non-tertian voicings, quartal chords, or experimental harmonies.

Worked examples

C E G → C major, root position. Intervals from C: M3, P5.
E G C → C/E (C major, first inversion). The root is still C but E is in the bass.
B D F → Bdim (B diminished triad). Intervals m3, dim5.
F A C E → Fmaj7. Intervals M3, P5, M7.
G B D F → G7 (G dominant seventh). Intervals M3, P5, m7.

Note that enharmonic equivalents (C# and Db) are treated as the same pitch class, so the displayed name uses the more common spelling from the matched template.

Tips for accurate results

Put the actual lowest-sounding note first — the tool uses the first note as the bass for inversion detection.
Sharps use # and flats use b; octave numbers are ignored (C3 and C5 are the same pitch class).
Duplicate notes (C E G C E) are deduplicated to pitch classes, so doubling does not affect the chord name.

All analysis runs locally in your browser.