Why does the chord from E flat use flats rather than sharps?

Because the spelling follows the root letter. Each quality is defined as letter steps plus semitone distances, so a chord built on E flat advances through the letters E, G, B and D and takes whatever accidentals are needed to reach the right pitches. The same notes from D sharp would need double sharps to stay spelled correctly.

Why do the add nine and dominant nine go beyond twelve semitones?

Because a ninth is a second an octave higher. The distance from the root is fourteen semitones and the letter advances by eight steps, which keeps the tone spelled as a ninth rather than as a second. That is also why the resulting note lands above the octave in the table.

What is the difference between a half-diminished and a diminished seventh?

One semitone at the top. The half-diminished seventh is a diminished triad with a minor seventh above it, while the fully diminished seventh squeezes that top note down to nine semitones. The first is common as a two chord in minor keys, the second is symmetrical and belongs to no single key.

Can I get an inversion or a different voicing?

The tones are always listed in root position, so the bass note is the root and the rest stack upward. To play another arrangement, take the names the tool gives and place them wherever suits the instrument; the pitch content is unchanged by voicing, only the register and the bass.

Is the frequency of each tone at modern pitch?

Yes, the frequencies follow the standard reference. If the material is at another tuning, take the note names from here and convert them with the note frequency calculator set to the reference you need, which shifts every tone by the same proportion.

Chord Calculator

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Chord Calculator spells any chord from a root note and a quality, and lists every tone with its MIDI number and frequency. The spelling follows the root letter, so a chord from E flat reads with flats rather than sharps.

What is Chord Calculator?

Choose a root and a quality from the list and the chord appears with every tone named, numbered and given in hertz.

The controls and the output:

A root field accepting a note with an octave, such as C4, E flat 3 or F sharp 2.
A quality selector covering fifteen forms: major, minor, diminished, augmented, both suspensions, three seventh shapes, the half-diminished, the diminished seventh, major and minor sixths, the add nine and the dominant nine.
A tone row naming the notes without their octave numbers, which is the way a chord is usually written.
A table of each tone with its MIDI number and its frequency in hertz.

Every quality is stored as a set of letter steps and semitone distances rather than as a list of note names, and that is what makes the spelling correct rather than merely serviceable. A dominant seventh on E flat takes the letters E, G, B and D and the semitone distances zero, four, seven and ten, which produces E flat, G, B flat and D flat. Spelling the same pitches from D sharp would produce D sharp, F double sharp, A sharp and C sharp, which sounds identical and is wrong in every practical sense. Because the letters advance by one degree at a time, every chord quality spells out with the right accidentals whatever root it is placed on, including roots that need sharps, flats or a mixture. The suspended forms replace the third rather than adding to it, which is why they are neither major nor minor; the half-diminished and diminished sevenths differ in one semitone at the top; and the add nine and dominant nine reach past the octave, which is why their semitone values exceed twelve. The MIDI numbers make the chord playable and the frequencies make it usable as a reference for tuning or synthesis.

What the tool does not do:

No voicing, so the tones are listed in root position rather than in any arrangement.
No inversions, so the bass note is always the root.
No audio, so the chord is not played back.
No progressions or key context, so nothing is suggested about where the chord belongs.
No omission or alteration beyond the fifteen qualities listed.
Nothing is uploaded, and the spelling is decided by the root letter you type.

Use it to check a spelling, to work out the notes of an unusual chord before writing it down, or to get the frequencies of a chord's tones for synthesis. When the relationship between just two of those notes is the question, the interval calculator names it, and when the chord belongs in a key rather than standing alone, the chord progression builder places it among the diatonic triads of that key. The three kinds of output are worth keeping separate in your head. The names tell you how to write the chord, the numbers tell you how a synthesizer or sequencer will address its tones, and the frequencies tell you where those tones actually sit, which is the figure needed when a chord has to line up with a filter, a resonance or an existing recording rather than with a keyboard.

How to use Chord Calculator

Type a root note with its octave, such as E flat 3.
Choose the chord quality from the selector.
Read the tone names, which follow the spelling of the root letter.
Use the MIDI and frequency columns if the chord is going into software or synthesis.

When to use Chord Calculator vs related tools

Chord Calculator is the tool for spelling a chord correctly and for getting its tones in numbers. Chord Progression Builder puts chords in the context of a key and renders a progression as audio, and Scale Generator supplies the scale a chord is drawn from. When only the distance between two of the chord's tones matters, Interval Calculator names it.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.