C# major
Major key. Scale: C#, D#, E#, F#, G#, A#, B#.
Octaves
Musical context
How the key relates to the chord, scale, mode and progression.
Theory
General info
- Name
- C# major
- Mode
- Major
- Tonic
- C#
- Key signature
7 sharps: C, D, E, F, G, A, B.
- Key character
- Scale degree 3 clearly distinguishes major from the parallel minor, while the leading tone strengthens V–I resolution. In equal temperament, tonic pitch alone does not determine mood; melody, harmony, register, tempo, and texture do.
- Overview
- The C# major key sets its stable tones and typical harmonic connections. Major keys are built on the Ionian mode (steps 2 – 2 – 1 – 2 – 2 – 2 – 1), minor keys on the Aeolian (2 – 1 – 2 – 2 – 1 – 2 – 2). The number of accidentals marks the key's position on the circle of fifths.
Key composition
1C#root
2D#major 2nd
3E#major 3rd
4F#perfect 4th
5G#perfect 5th
6A#major 6th
7B#major 7th
Key construction
- Interval formula
- C#WD#WE#HF#WG#WA#WB#
- Explanation
- The major scale follows the pattern whole, whole, half, whole, whole, whole, half. Its degrees form the key’s diatonic chords, while scale degree 3 defines the major quality.
Related keys
- Relative key
- A# minor
- Parallel key
- C# minor
- Reference mode
- C# Ionian (major)
Harmonic functions
TTonicI (C#), IV (F#)
SSubdominantii (D#m), v (G#m)
DDominantVI (A#)
- Overview
- Tonic is the stable centre of a key. Predominant function moves away from tonic and prepares dominant; dominant points toward resolution in tonic. The scheme Tonic → Predominant → Dominant → Tonic describes a basic functional progression but does not exhaust tonal harmony.
Chords by degree
Primary triads
- Tonic triad 1 – 3 – 5
- Subdominant triad 4 – 6 – 1
- Dominant triad 5 – 7 – 2
C#—E#—G#
G#—B#—D#
A#—C#—E#
Tensions & resolutions
VIIB#B#
IC#C#
In typical voice leading, the leading tone rises by semitone to tonic.
IVF#F#
IIIE#E#
In dominant harmony, scale degree 4 normally falls by semitone to 3.
IID#D#
IC#C#
Scale degree 2 may resolve downward by step to tonic.
Harmonic context
C# major is a major key. Diatonic chords are built on its seven scale degrees, and functional motion commonly connects tonic, predominant, and dominant.
Natural progressions
Cadences
VA#A#
IC#C#
An authentic cadence resolves dominant function into tonic.
IVG#G#
VA#A#
IC#C#
A complete functional progression connects predominant, dominant, and tonic.
This key on guitar 🎸
See how C# major looks on guitar.
Circle of fifths
Usage & Practice
Application in music
- Major-key diatonic chords support motion among tonic, predominant, and dominant without leaving the key.
- The authentic V – I progression emphasises the tonal centre through the leading tone and resolution of the dominant tritone.
- Patterns such as I – V – vi – IV can be transposed into this key without changing scale-degree relationships.
- Musical character depends not only on mode and tonic but also on melody, rhythm, register, tempo, texture, and timbre.
Practice
- Play the tonic chord (C#), then compare it with the other diatonic chords: tonic serves as the stable centre of the key.
- Alternate C# and A# (I – V – I), focusing on the leading tone resolving to tonic.
- Add G#m (IV): play G#m – A# – C# to hear predominant–dominant–tonic motion.
- Sing the key's scale, emphasizing degrees I, III and V — these are the anchor notes.
- Improvise a melody starting and ending on the tonic to reinforce the sense of center.
Keyboard Trainer
Reinforce it in practice — play and name notes on the interactive keyboard.