Free music tools
Song key and BPM finder
Quick answer
Open an audio file and the tool estimates its musical key and tempo in a few seconds. The key comes from a chromagram matched against Krumhansl–Schmuckler key profiles; the BPM comes from onset detection and autocorrelation. You get a confidence level, the relative major or minor, and half- and double-time readings, because those are the most common ways any detector can be off. It is free and your file is processed on your device, never uploaded.
- Free
- No sign-up
- Audio stays on your device
Last updated:
Try it now
MP3, WAV, M4A, OGG or FLAC. The file stays on your device.
Your file is analysed on this device and never uploaded.
How to use it
- Press Choose audio file and pick an MP3, WAV, M4A, OGG or FLAC file on your device.
- Wait a few seconds while your browser decodes and analyses it.
- Read the key and BPM, then check the confidence and the alternatives listed underneath.
- If you want to sing it in another key, open the free key changer or the vocal range test.
Honest limitations
- Songs that change key, use modes (such as Dorian or Mixolydian) or are mostly drums can give a less certain key result.
- Relative keys share the same notes (C major and A minor, for example), so the detector may name either one. Check which chord feels like 'home'.
- BPM can come out at half or double the tempo you tap, especially in ballads and drum-and-bass. Both readings are shown.
- Songs with a changing tempo, rubato or no clear beat get an average, low-confidence BPM.
Privacy: your audio never leaves your device
This tool runs entirely in your browser with the Web Audio API. Microphone input and the files you open are analysed in memory on your own device. Nothing is uploaded to MR Maker or any other server, nothing is recorded, and closing the tab discards everything.
Frequently asked questions
How do I find the key of a song?
Open the song file in this tool and it reports the most likely key, such as G major or E minor, with a confidence level. You can confirm it by playing the tonic chord along with the song: it should sound settled and final.
How accurate is the key and BPM detection?
On pop, rock and K-pop songs with a steady beat and a clear key it is usually right or off by a closely related key. The confidence label tells you when to double-check, and the alternatives show the most likely second choice.
Why does it say A minor when the song is in C major?
C major and A minor use the same seven notes, so they look almost identical to any detector. The tool always shows the relative key next to the result so you can pick the one that matches the song's home chord.
Why is the BPM half or double what I expected?
Beats can be felt at different levels, for example 70 or 140 BPM for the same groove. The tool picks the most likely one and lists half and double time so you can choose the one you count.
Which audio formats are supported?
Anything your browser can decode: usually MP3, WAV, M4A/AAC, OGG and FLAC. Protected streaming files and video-only formats are not supported.
Is my song uploaded anywhere?
No. The file is read and analysed by your browser on your own device. Nothing is sent to MR Maker or anyone else.
Want to sing this song without the original vocals?
MR Maker's paid AI vocal remover turns a song you upload into an instrumental (MR) for practice or performance, and can change its key. Credits are used per conversion and the cost is shown before you start.
Upload a song to MR Maker