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About this tool
Identify major and minor keys from sharps and flats, with instant scoring and the circle-of-fifths rule behind every answer.
A key signature quiz turns a printed group of sharps or flats into the major and minor key it represents, then tests you on it with instant scoring. It uses the circle of fifths and the two standard reading rules: the major key sits one semitone above the last sharp, and with two or more flats the second-to-last flat names the key. Built for music students, choir and band players and anyone sight-reading unfamiliar scores who wants the answer and the reasoning together.
Open Key Signature Quiz on AltFTool — it loads instantly in your browser.
Set Questions (1 to 30), choose Major keys, Minor keys or Mixed major and minor under 'Ask for', and tick 'Sharp signatures' or 'Flat signatures' under 'Include signatures'.
Answer each multiple-choice question, or press 'New question set' for a fresh randomised set — every answered question shows the circle-of-fifths rule behind the correct key.
Read your running score and accuracy percentage, press 'Copy result' to copy the summary, and check any signature in the 'All 15 key signatures' reference table.
Each result names the last sharp or second-to-last flat so you learn the shortcut, not the list.
Switch between naming the major key, the relative minor, or a mix of both in one set.
All fifteen signatures from seven flats to seven sharps stay on screen for checking.
Take the last sharp in the signature and go up one semitone: that is the major key. Four sharps end on D♯, so the key is E major, and the relative minor is C♯ minor, a minor third below.
With two or more flats, the second-to-last flat is the name of the major key. Five flats read B♭ E♭ A♭ D♭ G♭, so the second-to-last is D♭ and the key is D♭ major. One flat is the exception you memorise: B♭ alone means F major or D minor.
Fifteen in common-practice notation: seven flats through seven sharps plus the empty signature. Each one carries a major key and its relative minor, so the quiz covers 30 key names in total.
Sharps always follow F C G D A E B, each a perfect fifth above the last, and flats follow the reverse, B E A D G C F. The mnemonics are 'Father Charles Goes Down And Ends Battle' read forwards for sharps and backwards for flats.