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Calcimator

Chord Builder Calculator

Build chords from root note and chord type. See note composition and inversions.

About this calculator

Every chord is built from a fixed pattern of semitone intervals stacked above its root note. A major chord is root, +4, +7 semitones; a minor chord is root, +3, +7; and so on through diminished, augmented, and the four-note 7th chord qualities. This calculator takes your chosen Root Note and Chord Type, applies that interval pattern, and reports each resulting note as a semitone number from 0 (C) to 11 (B) -- Note 4 shows -1 when the chord only has three notes.

Inversion rotates which note sits at the bottom: root position keeps the root note lowest, while 1st, 2nd, or 3rd inversion cycles the lower notes up an octave one at a time (3rd inversion only applies to four-note 7th chords, since a triad has nothing left to rotate to a third position). Interval Pattern is a fixed fingerprint of the chord quality itself, shown as the dash-separated semitone offsets from the root (e.g. 0-4-7 for a major triad) -- Chord Type is the only input that changes it, since it's derived purely from the interval pattern before the root note or inversion are ever applied.

Inputs

Results

Note 1 (semitone)

0

Note 2 (semitone)4
Note 3 (semitone)7
Note 4 (semitone, -1 if N/A)-1
Interval Pattern (semitones)0-4-7
Voicing Code10
How to Use This Calculator
  1. Select the Root Note, Chord Type, and Inversion you want to build.
  2. Review Note 1 through Note 4 (semitone) for the resulting chord tones -- Note 4 shows -1 for three-note chords.
  3. Check Interval Pattern to see the chord quality's underlying semitone fingerprint, independent of root note.
  4. Use the chart to visualize the resulting notes and explore different root notes, chord types, and inversions.

What each input means

Root Note
The root note of the chord.
Chord Type
The chord quality to build from the root note.
Inversion
Which chord tone sits lowest. 3rd inversion only applies to four-note (7th) chords.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Root Note (0=C, 1=C#, ... 11=B) = 0, Chord Type = 1, Inversion = 0 = 3 input(s) provided
  2. Calculate Note 1
    Note 1
    0 = 0
  3. Calculate Note 2
    Note 2
    4 = 4
  4. Calculate Note 3
    Note 3
    7 = 7

Engine last updated . Checked against 4 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why do the notes show as numbers instead of letter names?

Each note is reported as its pitch class -- a semitone position from 0 (C) through 11 (B) -- which is unambiguous regardless of key. Pitch classes are not the same as letter names, though: on a sharp or flat root the correct spelling can need a double accidental. D# major, for instance, comes out as 3, 7, 10, but it is spelled D#-Fx-A#, not D#-G-A#, because a major triad always uses three alternating letter names. Read the numbers as intervals above the root (0, 4, 7 = root, major third, perfect fifth) and spell them by letter, rather than counting semitones up from C.

Why does Note 4 show -1 for a major or minor chord?

Triads (major, minor, diminished, augmented) only have three notes, so there's no fourth note to report. -1 is the calculator's placeholder for "not applicable" -- only the three 7th-chord qualities (dominant 7th, major 7th, and minor 7th) produce a real value there.

Does changing the Root Note change the Interval Pattern?

No. Interval Pattern is derived only from Chord Type -- it's a fingerprint of the chord's internal semitone spacing before the root note is applied. The same chord quality produces the same Interval Pattern no matter which root note or inversion you choose.

Can I use 3rd inversion on a major or minor chord?

The calculator will accept it, but a triad only has three notes to rotate through, so 3rd inversion collapses to the same result as 2nd inversion for major, minor, diminished, and augmented chords. 3rd inversion is only musically distinct on the three four-note 7th-chord qualities.

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