To find the key of a song, listen for the note that feels like home, then check which scale the other notes fit. The bass line is the fastest clue, because it often plays the root of each chord. If the bass is hard to hear in the full mix, the Bass Remover gives you a bass-only file that makes this much easier.
This guide shows four steps that work for any song. You need a piano, a keyboard app, or just your voice.
The key tells you which set of notes a song mostly uses, and which note is the center. A song in C major uses mostly the white keys on a piano and treats C as home. A song in A minor uses the same white keys but treats A as home.
That home note is called the tonic. Other notes feel like they are leaving it or returning to it. When a melody lands on the tonic, it feels finished.
The tonic is the note where the song feels at rest.
Some songs end on a fade or on a chord that is not the tonic. In that case, use the start of the chorus or the last line of a verse, where the melody often settles.
Bass notes are the easiest ones to track, because they are low and slow-moving. In a lot of songs, the bass plays the root of each chord, and the first and last bass notes of a section are often the tonic.
This does not always hold. Some bass lines walk around the chord, and some play the fifth instead of the root. Treat the bass as strong evidence and confirm it with the other steps.
The hard part is hearing the bass over drums and vocals, especially on small speakers. Here is how to isolate it with Unmix Studio:
Most tools on the site cost 1 credit per minute of song. In our own test, a 4 minute 44 second song split into 6 stems in 56 seconds and cost 5 credits. Heavy distortion and very low sub bass can leave a little bleed in the bass file, which will not stop you from finding the root notes.
Once you have a candidate tonic, check that the other notes fit. A major scale follows a fixed pattern of whole steps (W) and half steps (H):
W – W – H – W – W – W – H
Starting from C, that gives C D E F G A B, with no sharps or flats. Starting from G, the same pattern gives G A B C D E F-sharp, which has one sharp. Every major key has a relative minor that uses the same notes but starts three half steps lower. A minor, for example, shares all its notes with C major.
This table shows the common keys and how many sharps or flats they use.
| Sharps or flats | Major key | Relative minor |
|---|---|---|
| None | C | A |
| 1 sharp | G | E |
| 2 sharps | D | B |
| 3 sharps | A | F-sharp |
| 1 flat | F | D |
| 2 flats | B-flat | G |
| 3 flats | E-flat | C |
If the melody uses F-sharp and no other sharps, the song is in G major or E minor. Decide between the two by listening to which note feels like home. Major keys sound brighter, and minor keys sound darker or more serious.
If hearing the notes by ear is slow, you can let the computer write them down. The Audio to MIDI converter is free, runs in your browser, and does not upload your file.
Bass and voice are read one note at a time, which keeps the result readable. A piano part can be handled the same way. If a full mix is too busy, pull out the keys first with the Piano Extractor, then convert that file.
Raise the Shortest note setting if you see tiny stray notes. The notes you see tell you the scale, and the one the bass lands on most often is a strong guess for the tonic.
Once you have a guess, test it.
Songs sometimes change key, often by moving up a step near the end. If the key seems to shift in the middle, name the key for the section you are working on.
Listen for the note that feels like home, usually at the end of the song. Check the bass line for its root notes, then confirm that the melody fits the scale of that key.
Yes. Hum along, stop on the note that feels finished, and find it on an instrument. Play the matching scale over the song to check it.
Isolate the bass with the Bass Remover and listen to which note it returns to at the start of phrases. That note is often the tonic. Walking bass lines and chord inversions can mislead you, so check against the melody.
Yes. Convert a bass or melody recording with the Audio to MIDI converter and read the notes on the piano display. The notes that show up most often point to the scale.
Most tools cost 1 credit per minute of song, and the price shows on the button before you run it. New accounts get 5 free credits, enough for a song up to 5 minutes. If a split fails, the credits return to your account.