Charlotte Hayes
Music Analysis Technologist & DJ/Production Educator | Founder, BPMKeyFinder.com
My name is Charlotte Hayes. I built BPMKeyFinder.com because two numbers define more about how a song will mix, blend, and feel in a set than almost anything else: its tempo in BPM and its musical key. And yet, finding both accurately and instantly — without uploading files to a remote server, without creating an account, without waiting — has been harder than it should be for the people who need it most.
A DJ preparing a set needs to know whether a new track is in A minor or F# major before deciding which songs can transition into it smoothly. A producer needs to know the key of a sample before committing to a session built around it. A songwriter needs the BPM of a reference track before recording a new idea at that tempo. A remixer needs both the key and tempo of the original before starting work on a new version.
BPMKeyFinder.com was built to answer all of those needs instantly, accurately, and privately — with the audio file never leaving your device.
What I Research and Write About
My work on BPMKeyFinder.com covers four areas:
Audio analysis algorithms for BPM and key detection. BPM detection and key detection are two fundamentally different signal processing problems, each requiring its own algorithmic approach. BPM detection identifies the periodic pulse in a track’s onset energy — the rhythmic pattern produced by drums, bass hits, and other percussive events — using onset detection followed by autocorrelation or beat tracking to identify the dominant beat period. Key detection is a harmonic analysis problem: the algorithm extracts a chromagram — a 12-element pitch class profile summarising how much energy is present at each of the twelve pitch classes (C, C#, D, D#, E, F, F#, G, G#, A, A#, B) across the track — and matches that profile against the 24 major and minor key templates established by the Krumhansl-Schmuckler model of tonal cognition. I research how both algorithms work, what affects their accuracy, and why certain types of music challenge each approach.
The Camelot Wheel and harmonic mixing. The Camelot Wheel is the standard DJ system for harmonic mixing. It maps all 24 musical keys to a grid of numbers (1–12) and letters (A for minor, B for major), allowing DJs to identify compatible key combinations without deep music theory knowledge. Keys sharing the same number are relative major/minor pairs. Adjacent numbers on the wheel represent keys that share many notes and blend naturally in transitions. The +7 rule (moving seven positions clockwise) gives an energy-boost modulation effect. I research the music theory behind harmonic compatibility — why relative major and minor mix smoothly, what circle-of-fifths relationships underlie the Camelot numbering system, and how key transitions create different emotional and energetic effects in a set.
Music production and DJ applications of BPM and key data. In music production, knowing a sample’s key before loading it into a project prevents harmonic clashes that force time-consuming transposition work. Knowing the BPM before building a drum arrangement prevents grid misalignment that creates timing issues throughout a session. For DJs, BPM and key data are the foundation of professional set preparation — Rekordbox, Traktor, Serato, and Virtual DJ all incorporate BPM and key analysis precisely because this information is essential to building coherent sets. I research how BPM and key data are used across the full range of music production, DJ performance, songwriting, remixing, and sample library management workflows.
Accuracy, limitations, and honest disclosure. Browser-based audio analysis is genuinely powerful — but it has real accuracy limitations that users deserve to know. BPM detection is highly accurate for music with clear rhythmic patterns (typically ±1 BPM) but can produce half-time or double-time results for trap, hip-hop, and music with ambiguous rhythmic structure. Key detection accuracy is typically above 80% on popular music genres but is lower for music with frequent key changes, modal compositions, atonal music, or short audio clips that do not provide enough harmonic context for reliable analysis. I document these limitations clearly because a DJ who trusts an incorrect key result and plans a transition around it will discover the problem on the dancefloor — the worst possible moment.
Why I Built This Tool
Most BPM and key finders online fall into one of two categories: tools that are fast but shallow (they give you a number with no context for what it means or how accurate it is), or tools that are accurate but require account creation, file upload to remote servers, or payment for unlimited use.
BPMKeyFinder.com was built to be neither of those things. It processes your audio file locally in your browser — the file never leaves your device. It gives you BPM, key, and Camelot Wheel notation in one result. And it documents what the results mean, how accurate they are likely to be, and what to do when the result seems wrong.
Accuracy Standards
Every page on this site meets the following standards:
- BPM detection accuracy claims are grounded in the established performance of onset detection and beat tracking algorithms for music with clear rhythmic patterns
- Key detection accuracy claims reflect the documented performance of chromagram + key profile matching (Krumhansl-Schmuckler and EDMA approaches) on popular music genres
- Camelot Wheel information is accurate to the published standard used in Rekordbox, Traktor, and Serato
- Accuracy limitations — half-time/double-time ambiguity, key change handling, short file limitations — are clearly disclosed on every relevant page
- File handling privacy — audio files processed locally with no server transmission — is documented accurately
If you find an error anywhere on this site, please report it via the Contact page. All corrections are reviewed personally and applied promptly.
Tools and Content on This Site
- BPM Key Finder — the flagship tool: upload an audio file and instantly receive BPM, musical key, and Camelot Wheel notation
- How It Works — technical explanation of BPM detection, key detection, and Camelot Wheel methodology
- BPM Key Finder FAQ — common questions about BPM, key detection, Camelot Wheel, and file handling
- Troubleshooting — fixes for file upload issues, unexpected results, and unsupported formats
- Educational articles on harmonic mixing, BPM and key in music production, Camelot Wheel usage, and DJ preparation
Get in Touch
Contact: bpmkeyfinder.com/contact
How the tools work: bpmkeyfinder.com/how-it-works
Editorial standards: bpmkeyfinder.com/editorial-guidelines
Charlotte Hayes is the founder and sole author of BPMKeyFinder.com. All tool pages, educational content, and supporting pages on this site are written and maintained by Charlotte Hayes. Last updated: June 2026.