Same sound, different spelling

One piano key can have two names

C-sharp and D-flat reach the same piano key in twelve-tone equal temperament. That does not make the two names interchangeable in every explanation. Written music uses letter names to show relationships, and those relationships can be lost if every black key is renamed with a sharp.

Think of a note name as more than a location. It includes a letter and an accidental; an octave label adds a particular register. The sounding pitch lets you hear the result, while the spelling helps you read why the note belongs there.

Keep a third looking like a third

C minor contains C, E-flat and G. Its third needs an E letter because C–D–E spans three letter names. Writing C, D-sharp and G would reach the same keys, but C to D-sharp would be written as an augmented second rather than a minor third.

This matters when you compare C major and C minor. E changes to E-flat while C and G stay fixed. The spelling makes the one-degree alteration visible. A keyboard that labels the middle key D-sharp can still play the correct sound, but its label is less useful for explaining this chord.

Six semitones can describe different intervals

C to F-sharp and C to G-flat both span six semitones. Count the letters inclusively: C–D–E–F makes a fourth, while C–D–E–F–G makes a fifth. The first is an augmented fourth and the second a diminished fifth.

A tool that reports only “six semitones” gives a correct distance but an incomplete written interval. ChordLilt keeps both the semitone distance and the spelled relationship so you can compare them.

Accidentals can land on white keys

F-sharp major seventh is F-sharp, A-sharp, C-sharp, E-sharp. E-sharp sounds on the F key, but it is the seventh-degree letter above F-sharp. Replacing it with F would obscure the F–A–C–E chord structure.

The same principle explains C diminished seventh: C, E-flat, G-flat, B-double-flat. The last note sounds like A in equal temperament, yet B-double-flat shows the diminished seventh above C. A double flat lowers its letter by two semitones; it is not a formatting error.

D-sharp natural minor offers another useful check: D-sharp, E-sharp, F-sharp, G-sharp, A-sharp, B and C-sharp. The second degree is E-sharp, not F. Replacing it with F would make the written list use F twice and omit E. The piano keys would still sound, but the notation would stop showing one letter for each scale degree.

A reference catalogue still needs a consistent choice

Many enharmonic keys have useful musical roles. A catalogue can choose one spelling per pitch class for a particular family without claiming the alternatives are wrong. ChordLilt’s public references make that editorial choice, while the explorers preserve supported spellings selected by the user.

Do not replace the spelling in a saved project merely because another page uses an enharmonic name. Keep the user’s harmonic context intact. The same caution applies when transposing: choose a readable destination spelling, then check the actual interval roles.

Check the name and the sound together

Use the interval finder to compare C–F-sharp with C–G-flat. Then open F-sharp major seventh and identify the E-sharp key. Listen to both examples while reading their labels.

1. Count the letter distance before counting semitones.
2. Check which degree the note represents in the chord or scale.
3. Compare the piano position without changing the written name.
4. Include the original spelling when saving or exporting the example.