Chord Calculator - Triad and Seventh Chord Builder

A chord calculator is a music-theory reference tool that takes a root note and a chord type and returns the chord notes, the scale-degree formula, and the standard chord symbol. It covers the 14 most common triads and seventh chords in tonal music.

• • Learn chord construction: Pick a root and a chord type and read the scale-degree formula (1, 3, 5, 7) so you can see exactly how each chord is built from the major scale.
• • Look up an unfamiliar chord symbol: Pick the root and the chord type from the dropdowns to get the notes, the symbol, and the largest interval in semitones for any of the 14 most common chord qualities.
• • Practice chord inversions and voicings: Use the note list as a starting point to rearrange chord tones on guitar or piano and to practice inversions, drop voicings, and open-position shapes.
• • Write chord charts and lead sheets: Copy the standard chord symbol (Cmaj7, C7, C°7) into a chord chart, lead sheet, or notation file so the rest of the band reads the same chord name.

Once the chord is built, the Chord Transposer moves the same chord and any progression that contains it into a new key while keeping the quality and the bass note intact.

The tool combines the root note and the chord type through a single lookup table that maps each chord quality to a list of semitone intervals and a scale-degree formula. It walks the chromatic scale from the root by the number of semitones in each interval and returns the resulting note name, using the same enharmonic spelling as the chosen root.

• rootNote: The pitch class for the root, picked from a 17-value list covering the 12 pitch classes with explicit sharp and flat spellings (C, C#, Db, D, D#, Eb, E, F, F#, Gb, G, G#, Ab, A, A#, Bb, B).
• chordType: The chord quality, picked from a 14-value list covering major, minor, augmented, diminished, sus2, sus4, dominant 7, major 7, minor 7, minor-major 7, diminished 7, half-diminished 7, major 6, and minor 6.
• intervals[type]: A list of semitone offsets from the root. Major triad is [0, 4, 7], dominant 7th is [0, 4, 7, 10], diminished 7th is [0, 3, 6, 9].
• chordFormula[type]: The scale-degree formula with the accidentals the chord requires. Major triad is 1, 3, 5; minor triad is 1, ♭3, 5; dominant 7th is 1, 3, 5, ♭7; diminished 7th is 1, ♭3, ♭5, ♭♭7.

According to Wikipedia - Major scale, the major triad is built by stacking the 1st, 3rd, and 5th degrees of the major scale, which produces the semitone intervals 0, 4, and 7 above the root.

Both calculators walk a fixed arithmetic pattern from a known starting point, the same way the Arithmetic Sequence Calculator walks any arithmetic sequence from its starting term and common difference to return the next n terms.

Four ideas from music theory explain how the tool turns a root and a chord type into a complete chord, and they appear in the result row for every chord the user builds.

A pitch class wraps around the chromatic scale at the octave, the same way modular arithmetic wraps a counter back to zero, and the Modulo Calculator handles any mod n operation in one step.

Five short steps take you from a root note and a chord type to a complete chord symbol, a list of chord notes, and the scale-degree formula that built it.

1. 1 Pick the root note: Choose the pitch class for the root of the chord from the 17-value dropdown. Pick the sharp or flat spelling that matches the key you are working in.
2. 2 Pick the chord type: Choose one of the 14 chord qualities from the chord type dropdown. Start with the major triad, then move to minor, dominant 7, or major 7.
3. 3 Read the chord symbol and notes: The chord symbol row (Cmaj7, C7, C°7, Cø) and the chord notes row (e.g. C, E, G, B) both update as you change inputs.
4. 4 Read the chord formula: The formula row shows the scale degrees that produced the chord, with accidentals rendered as needed. Use this row to compare two chord types side by side.
5. 5 Check the largest interval: The largest interval row shows the number of semitones from the root to the highest note. Triads return 7, dominant 7ths return 10, major 7ths return 11, and diminished 7ths return 9.

Practical example: a piano student learning C major needs to know what makes a Cmaj7 different from a C7. They set the root to C, switch the chord type from Major 7th to Dominant 7th, and compare. The major 7th returns C, E, G, B with formula 1, 3, 5, 7, while the dominant 7th returns C, E, G, Bb with formula 1, 3, 5, ♭7.

The interval ratios behind the chord notes come from the same family of small-integer ratios that define musical intervals in just intonation, and the Ratio Calculator simplifies any pair of numbers and finds equivalent ratios in one step.

Four practical reasons to use the chord tool instead of paging through a chord dictionary or working the intervals out by hand.

• • Faster chord lookup: Pick a root and a chord type, and the tool returns the chord symbol, the chord notes, the formula, and the largest interval in one step.
• • Consistent enharmonic spelling: The result row uses the same enharmonic spelling as the chosen root, so a Db chord reads Db, F, Ab and a C# chord reads C#, F, G# without mixing sharps and flats.
• • Visible scale-degree formula: The formula row shows the scale degrees that built the chord, so a learner can see why a dominant 7th is 1, 3, 5, ♭7 and a major 7th is 1, 3, 5, 7 without memorizing the interval patterns separately.
• • Reference chart and practice aid in one: The same tool that returns the notes for a single chord also doubles as a reference chart for the 14 most common chord qualities, so the user can switch chord types and compare the result rows side by side while practicing.

The same scale-degree framework that drives a single chord also drives an entire chord progression, where several chord symbols stack on the circle of fifths to form the harmonic backbone of a song.

The semitone intervals behind the chord follow the same proportional logic that puts the golden ratio inside well-tempered scales and instrument body proportions, so the chord calculator doubles as a way to check that any chord type sits in the same proportional family, and the Golden Ratio Calculator returns phi plus the longer and shorter segments from any single input.

Three practical variables change the result row and two approximation caveats explain why the tool is a music-theory reference rather than a substitute for ear training.

• • The tool is a music-theory reference, not an ear-training tool. It does not test whether the player can hear the difference between a major 7th and a dominant 7th, and it does not teach voice leading or extended harmony.
• • The result row uses the 12-tone equal-tempered scale. Microtonal intervals, just intonation, and non-Western tunings are not represented.

Enharmonic spelling is a notation choice, not a music choice. A Db major triad and a C# major triad contain the same three pitch classes (Db/F/Ab vs C#/F/G#), and an equal-tempered instrument plays them identically.

According to Wikipedia - Dominant seventh chord, the dominant seventh chord is built from the 1st, 3rd, 5th, and flattened 7th degrees of the major scale, which produces the semitone intervals 0, 4, 7, and 10 above the root and is the most common seventh chord in popular music.

According to Wikipedia - Chord (music), a chord in music is a set of multiple notes, usually played simultaneously, with triads being the most fundamental family and seventh chords being the most common extension.

Enharmonic equivalence between a C# chord and a Db chord is the same kind of equality between different-looking representations of the same value, and the Equivalent Ratio Calculator reduces any pair of ratios to a single canonical form in one step.