# FifthCircle — Key Signature Calculator > Musical key and key signature calculator using the Circle of Fifths. (iPhone/iPad app by Chris Crossen.) - Source: https://appshunter.io/ios/app/fifthcircle/id1526216017 (this page in markdown: same URL + `.md`) - Developer: [Chris Crossen](https://appshunter.io/developer/1526216020) - Category: Music, Music, Education - Price: $1.99 - Rating: 5.00/5 from 1 App Store ratings - Age rating: 4+ - Requires: iOS 14.0 · 7 MB - Languages: English - Released: 2020-08-06 - Data updated: 2026-07-05 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/fifthcircle/id1526216017/reviews.md ## What is FifthCircle? Convert between musical key and musical key signature using the Circle of Fifths. You can convert either from the other. Keys are selected by tapping on the piano keyboard graphic. Key signatures are selected by tapping on the rotate buttons above the musical staff graphic. Tapping on a piano key will select that key and display the major and minor key names and the key signature for that key. Ambiguous cases (C Sharp versus D Flat for example) are resolved by presenting a dialog where you can select your choice. Tapping on the counterclockwise rotate button will move counterclockwise on the Circle of Fifths. For example from the key of C you will rotate left to one flat (Key of F). Another tap will rotate to two flats (Key of B Flat). Tapping on the clockwise rotate button will move clockwise on the Circle of Fifths. From the key of C you will rotate right to one sharp (Key of G). Another tap will rotate to two sharps (Key of D). Regardless of which direction you are moving around the Circle of Fifths, if you continue tapping you will eventually return to where you started. On the Quiz tab you can practice your key signature recognition for both treble and bass clefs. You can also practice note recognition with the Ear Training option. ## Key features - Circle of Fifths key conversion - Key signature calculation - Interactive piano keyboard - Rotate clockwise/counterclockwise - Ambiguous key selection dialog - Key signature quiz (treble/bass clef) - Ear training for note recognition ## Frequently asked questions about FifthCircle ### What is FifthCircle used for? FifthCircle is a tool that helps you convert between musical keys and their corresponding key signatures using the Circle of Fifths. It also includes a quiz section to practice key signature and note recognition. ### How do I select a key in FifthCircle? You can select a key by tapping on the piano keyboard graphic within the app. This will display the major and minor key names and the associated key signature. ### Can FifthCircle help me practice music theory? Yes, FifthCircle has a Quiz tab where you can practice key signature recognition for both treble and bass clefs, as well as practice note recognition with the Ear Training option. ### What devices does FifthCircle support? FifthCircle is available for iPhone and iPod devices. It was last updated on October 10, 2024, with version 3.0. ### Is FifthCircle free to download? No, FifthCircle is a paid application. It is priced at $1.99 and does not contain advertisements or in-app purchases. ### Does FifthCircle have ads? No, FifthCircle is ad-free. The app was developed by Chris Crossen and is rated for ages 4 and up. ### How does FifthCircle handle ambiguous keys like C and Db? When an ambiguous key is selected, FifthCircle presents a dialog box allowing you to choose between the possible enharmonic equivalents, such as C Sharp or D Flat. ### How often is FifthCircle updated? FifthCircle was last updated on October 10, 2024, indicating active development and support. The current version is 3.0. ## Version history (last 5 releases) ### 3.0 — 2024-10-10 Improved user interface and additional statistics ### 2.8 — 2021-08-06 FifthCircle now runs on your M1 Mac. ### 2.7 — 2021-05-18 Your cumulative score is now maintained. ### 2.6 — 2021-05-02 Ear Training has been added to the Quiz tab. When you select the Ear button on the Quiz tab, a note is played and you select the note by tapping on the piano keyboard graphic. You may repeat the note as many times as you like by tapping on the Replay button before making your selection. As with the treble and bass key signature quizzes, running totals are kept of your progress. ### 2.5 — 2020-11-12 Ear Training has been added to the Quiz tab. When you select the Ear button on the Quiz tab, a note is played and you select the note by tapping on the piano keyboard graphic. You may repeat the note as many times as you like by tapping on the Replay button before making your selection. As with the treble and bass key signature quizzes, running totals are kept of your progress. ## Apps similar to FifthCircle | App | Rating | Price | Category | | --- | --- | --- | --- | | [UltimateScale](https://appshunter.io/ios/app/ultimatescale/id1631310626) | — | Free | Music | | [Music Scales and Keys](https://appshunter.io/ios/app/music-scales-and-keys/id6447535940) | 3.3 (4) | $0.99 | Music | | [Star 94.1 FM](https://appshunter.io/ios/app/star-941-fm/id1634138342) | — | Free | Music | | [BB Accordions](https://appshunter.io/ios/app/bb-accordions/id6456844669) | — | Free | Music | | [Synthy](https://appshunter.io/ios/app/synthy/id6450637444) | 5.0 (1) | Free | Music | | [Polyphono](https://appshunter.io/ios/app/polyphono/id6450939490) | — | Free | Music | ## More apps by Chris Crossen - [ChordInvert](https://appshunter.io/ios/app/chordinvert/id1549606631) All apps by Chris Crossen: https://appshunter.io/developer/1526216020 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-05.*