1 Sharp Is What Key? G Major / E Minor
One sharp is G major, or E minor. The single sharp is F sharp, written on the top line of the treble stave, and it is the only accidental in either scale.
1 sharp
G major / E minor
The last sharp written is F♯. Go up one semitone from it and you have the major key: G major.
G major scale
G A B C D E F♯
E minor scale (relative minor)
E F♯ G A B C D
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G major scale
G A B C D E F♯
E minor scale
E F♯ G A B C D
The rule, on the case it is easiest to check
The rule for sharp signatures is: find the last sharp written, go up one semitone, and that is the major key. Here the last sharp is the only sharp — F sharp — and a semitone above F sharp is G. The key is G major.
This is worth doing deliberately once, on this signature, because it is the case where you can verify the answer against something you already know rather than trusting the rule. G major is G A B C D E F sharp. Play it and the F sharp is unmistakable: without it the seventh degree would be a whole tone below the tonic instead of a semitone, and the scale would not sound major at all.
The relative minor is always three semitones below the major tonic, which puts it on E. E minor uses the same seven notes starting from E.
Why guitarists meet this signature early
E minor is the most open key on a guitar in standard tuning. Of the six open strings — E A D G B E — every single one belongs to the E natural minor scale, and two of them are the tonic itself. An E minor chord requires two fingers and lets four strings ring.
G major, sharing the signature, is nearly as generous: the open G, B, D and both E strings are all scale tones, and the standard open G chord uses three fretted notes with three strings ringing. This is why an enormous amount of beginner guitar material is written in G or E minor rather than in C — the instrument's own tuning is doing half the work.
The fiddle and session repertoire
In Irish and Scottish traditional music, G and D are the two central keys, and a large proportion of the standard session repertoire sits in one or the other. The reason is the instrument: a fiddle's open strings are G, D, A and E, so a tune in G can use the open G as a tonic drone and the open D and A as strong scale tones.
That repertoire is largely traditional and out of copyright, which makes it unusually good practice material for this signature specifically — the tunes are freely available in notation, they are written in G, and they use the F sharp constantly enough that it stops being something you have to remember.
One sharp, and the two chords that come with it
The seven diatonic chords of G major run G, A minor, B minor, C, D, E minor and F sharp diminished. Two of those are worth noticing for practical reasons.
The D chord is the fifth degree, and with the F sharp in the signature it is major, which is what gives G major a strong pull home. In E minor the same chord appears as the fifth degree too, but as a minor chord — which is exactly why so much E minor writing raises the D to a D sharp to make it major, producing an accidental the key signature does not account for.
The seven chords of G major
Every major key produces the same pattern of chord qualities — major on the first, fourth and fifth degrees, minor on the second, third and sixth, diminished on the seventh. Only the names change.
Questions people ask about this signature
- One sharp is what key?
- G major, or E minor. Both use the same seven notes and the same single sharp; which one a piece is in depends on which note it resolves to.
- Where exactly is the F sharp written?
- On the top line of the treble stave, and on the fourth line up in the bass stave. Its position is fixed by convention, not by which octave the music actually uses — the signature applies to every F in every octave.
- How do I tell G major from E minor at a glance?
- Look at the last chord or bass note, and look for D sharps in the body of the music. A piece in E minor will usually raise its seventh degree at cadences, and that produces D sharps that a piece in G major has no reason to contain.