Key signatures: which notes are sharp or flat, and remembering them
A key signature is a set of sharps or flats at the start of each line. It tells you which notes to play sharp or flat for the whole piece, so the composer doesn't have to mark every one. Most wrong notes in young bands aren't misread letters. They're notes that should have been sharp or flat because of the key signature.
What a key signature does
A flat on the B line in the key signature means every B is B♭, in every octave, until the key signature changes. The same goes for sharps. Key signatures always appear in the same order, so once you learn the order you can read any of them quickly.
The order of sharps and flats
Sharps always appear in this order: F C G D A E B. Flats are the same order backwards: B E A D G C F. A key with three flats always has B♭, E♭, and A♭, never any other three. Sometimes one pitch has both a sharp name and a flat name, like F♯ and G♭. See Enharmonic notes and the chromatic scale.
- Sharps: "Father Charles Goes Down And Ends Battle"
- Flats: "Battle Ends And Down Goes Charles' Father"
- The first four flats also spell BEAD.
Naming the key
Two quick rules name most major keys:
- Sharp keys: the last sharp is one half step below the key. Last sharp F♯ means G major. Last sharp C♯ means D major.
- Flat keys: the second-to-last flat is the key. Flats B♭ E♭ A♭ mean E♭ major. One flat (B♭ only) is F major, which you just memorize.
- No sharps or flats is C major.
Common band keys
Band music is mostly written in flat keys. Because many band instruments transpose, the same piece shows a different key signature on different parts. Here are the four keys you'll see most, by instrument group:
| Concert key | C instruments | B♭ instruments | E♭ instruments | F horn |
|---|---|---|---|---|
| B♭ (2 flats) | B♭: 2 flats | C: none | G: 1 sharp | F: 1 flat |
| E♭ (3 flats) | E♭: 3 flats | F: 1 flat | C: none | B♭: 2 flats |
| F (1 flat) | F: 1 flat | G: 1 sharp | D: 2 sharps | C: none |
| A♭ (4 flats) | A♭: 4 flats | B♭: 2 flats | F: 1 flat | E♭: 3 flats |
C instruments include flute, oboe, bassoon, trombone, baritone (bass clef), tuba, and mallets. B♭ instruments include clarinet, trumpet, tenor sax, and bass clarinet. E♭ instruments include alto and bari sax. For why parts are written in different keys, see Concert pitch and transposing instruments.
Accidentals inside a measure
An accidental is a sharp, flat, or natural written next to a note in the music. It overrides the key signature for that note until the end of the measure. The bar line cancels it, and the key signature takes over again.
- An accidental applies to later notes on the same line or space in that measure.
- A tie carries the accidental across the bar line to the tied note only.
- A courtesy accidental (sometimes in parentheses) is a reminder. It doesn't change anything.
Remembering them while you play
- Check the key signature first whenever you sight-read. It's one of the first things on the sight-reading checklist.
- Before you play, say the key signature out loud: "B♭ and E♭."
- Play the scale for that key first. Your fingers learn which notes change.
- Circle the first note in the piece that the key signature affects.
- Watch for key changes: a double bar line with a new key signature.
Knowing the letter names instantly makes all of this easier. Use Note Trainer to build that speed, then apply the key signature on top.