Key signatures
Read the sharps or flats at the start of the line and know the key instantly. · 15 min
What a key signature does
Instead of writing the same accidentals over and over, music lists them once at the start of every line: the key signature. Each sharp or flat in it applies to that letter in EVERY octave, for the whole piece (until a new key signature).
Example: one sharp on the F line means every F is played F♯.
Order of sharps and flats
Sharps are always added in this order: F C G D A E B (Father Charles Goes Down And Ends Battle).
Flats are the reverse: B E A D G C F (Battle Ends And Down Goes Charles' Father).
Naming the major key
Sharps: take the last sharp and go up one half step. Last sharp C♯ → key of D major.
Flats: the second-to-last flat is the key. Flats B♭ E♭ A♭ → E♭ major. Memorise one exception: one flat (B♭) = F major.
No sharps or flats = C major.
| Key signature | Major key / relative minor |
|---|---|
| None | C major / A minor |
| 1♯ (F) | G major / E minor |
| 2♯ (F C) | D major / B minor |
| 3♯ (F C G) | A major / F♯ minor |
| 4♯ (F C G D) | E major / C♯ minor |
| 1♭ (B) | F major / D minor |
| 2♭ (B E) | B♭ major / G minor |
| 3♭ (B E A) | E♭ major / C minor |
| 4♭ (B E A D) | A♭ major / F minor |
Major or minor?
Every key signature serves two keys: a major and its relative minor (three half steps lower). To decide which, look at the first and last notes and chords. Minor pieces also often raise the 7th note with an accidental — G♯ in A minor, D♯ in E minor.
Check yourself
You'll see immediately whether each answer is right, and why.
Which major key has this signature?