C# Major
Key Signature
| Property | Value |
|---|---|
| Tonic | C# |
| Mode | Major |
| Accidentals | 7 sharps |
| Key Signature Notes | F#, C#, G#, D#, A#, E#, B# |
C# major has seven sharps and is enharmonically equivalent to Db major. It is rarely used in practice but appears in some pieces where sharp notation is preferred throughout.
Diatonic Chords
The seven diatonic chords of C# Major — each built on a scale degree using only the notes of the key signature:
| Degree | Roman Numeral | Chord Type | Chord |
|---|---|---|---|
| 1 | I | Major | C# Major |
| 2 | ii | Minor | D# Minor |
| 3 | iii | Minor | F Minor |
| 4 | IV | Major | F# Major |
| 5 | V | Major | G# Major |
| 6 | vi | Minor | A# Minor |
| 7 | vii° | Diminished | C Diminished |
Related Keys
- Relative Minor
- A Sharp Minor — shares the same key signature.
- Parallel Minor
- C Sharp Minor — same tonic, different key signature.
See all key relationships on the Circle of Fifths.
Scales in C# Major
Common scales built from the C# tonic:
Transposing Instrument Context
Sharp-key signatures like C# Major are comfortable for open-string instruments (guitar, violin). Bb instruments (trumpet, clarinet, tenor saxophone) read in D# major to sound C# Major. Eb instruments (alto saxophone, Eb clarinet) read in A# major to sound C# Major. Standard guitar tuning (E A D G B E) resonates naturally in C# Major.