How to Find the Key of a Song
A quick guide to using showkeys — the free browser-based key & BPM finder.
Open the Key Finder →What is a song key?
A song's key defines the set of notes it uses and the note it feels most "at home" on. Most Western music uses one of 24 keys — 12 major and 12 minor. Knowing the key helps you play along, transpose, write chord progressions, and understand why certain notes sound right together.
How showkeys detects the key
showkeys works by elimination. You play or click melody notes on the on-screen piano, and the app checks each of the 24 major and minor scales to see which ones contain all the notes you've selected. As you add more notes, impossible scales are ruled out until the key is identified.
- Listen to a short section of the song and pick out 3–5 distinct melody notes.
- Click those notes on the showkeys piano keyboard.
- The results panel updates in real time — often narrowing to one or two candidates.
- Click any matching scale to lock it and hear how it sounds.
Detecting BPM with tap tempo
Press Spacebar in time with the beat of the song — once per beat for at least 4 taps. showkeys calculates the interval between taps, uses a rolling median to filter outliers, and displays the smoothed BPM next to the key result. Press Esc to reset everything and start over.
Keyboard shortcuts
You can enter notes without touching the mouse:
Keys map chromatically: A=C, W=C#, S=D, E=D#, D=E, F=F, T=F#, G=G, Y=G#, H=A, U=A#, J=B
Manual mode
Use the scale dropdown in the footer to lock into a specific key. In manual mode,
the piano highlights all notes in that scale so you can hear and visualize it.
You can also preload a scale via URL: ?scaleSelector=cmaj for C Major,
?scaleSelector=fsmin for F# Minor, etc.
Frequently asked questions
- What if multiple scales match?
- That's normal — most short note sequences fit several keys. Add more melody notes to narrow it down, or listen to which root note the song resolves to.
- Why can't I find the key from just one or two notes?
- Almost every note belongs to many different scales. You need at least 3–4 notes to meaningfully eliminate candidates, and 5–6 to reliably identify the key.
- Does showkeys support modes (Dorian, Phrygian, etc.)?
- Not yet — it currently matches the 12 natural major and 12 natural minor scales. Modal support is on the roadmap.
- How accurate is the BPM detection?
- Tap tempo works best for steady-tempo music. showkeys uses a rolling median of up to 8 intervals and exponential smoothing, so a few off-beat taps won't break the reading. For irregular or rubato music, results will vary.
- Does it work on mobile?
- Yes — the piano keyboard and tap tempo both work on touch devices. The layout adapts to smaller screens automatically.