How do you read a key from its accidentals?
Counting the sharps or flats printed at the start of a staff is enough to name the key. Enter the count and the type, and this page returns the major key, the relative minor that shares the same signature, and the order in which the accidentals are written.
The basis is the circle of fifths. Sharps are always added in the order F♯, C♯, G♯, D♯, A♯, E♯, B♯, and flats in the order B♭, E♭, A♭, D♭, G♭, C♭, F♭. Every added sharp moves the major key a perfect fifth up and every added flat moves it a perfect fifth down, so the count maps one to one onto the key name. The relative minor sits a minor third below the major and shares the signature.
Only counts from 0 to 7 are covered. A signature alone cannot say whether a piece is major or minor, so use the tonic and the final chord to decide. Pieces built on church modes, pieces full of accidentals outside the signature and frequent key changes are not analyzed here. As of October 2026 the ordering above is the standard notation convention taught worldwide.
Frequently Asked Questions
Three sharps give A major, with f♯ minor as the relative minor. They are written F♯, C♯, G♯, so the last one added is G♯.
The signature cannot tell you. Look at the chord the piece ends on and the note it keeps returning to as home.
They are enharmonic spellings: the pitches on a keyboard match and only the notation differs. Six sharps spell F♯ major, six flats spell G♭ major.