How to Find the Key for a Melody

If you start a song with a melody, finding a chord progression or creating an arrangement for that melody can be a challenge.

One way to make this process a lot easier is to figure out the notes and key for the melody.

If you know your scales and keys well, the best way to find the key is to just work out what scale your melody is in on your instrument. But for many people this is easier said than done.

In this post, we’ll look at two ways to find the key of your song without knowing much about music theory, scales, or keys.

The first way just requires an instrument (easiest if it’s a keyboard) and involves determining which note in your melody sounds most like “home”.

The second way uses specialized software to do most of this work for you. If you just want to quickly determine a key and don’t mind using software to do it for you, you can skip to this section.

Contents

The quick way to guess the key without software

Without starting up any software, we can use a rough approach to guess the key for a melody.

If this is a melody you’re singing, you’ll need to work it out on a keyboard. We’ll consider ways to get around this later, but for this technique you need to play the melody with your right hand on a keyboard.

Once you can play the melody, look at all of the notes you’re playing. If it helps you remember, you can write them down or label them.

One at a time, try playing each of these notes with your left hand on a lower octave as you play the whole melody with your right hand in the original octave.

If you’re not familiar with playing octaves, it basically means you play the same note further to the left on the keyboard. For example, here is F in two different octaves:

So take each note in the melody and try playing it one octave down while playing the whole melody in your right hand.

As you do, pay attention to whether that note in your left hand feels like “home”.

Does it seem to ground the melody and maintain a sense of stability? If so, it might be the root note of your key.

If you don’t know the names of the notes on the keyboard, then you can use stickers to label them like this:

You might know by ear (or some other means) whether your melody is major or minor. If so, then you are now ready to guess the key.

For example, if you know the melody is major, and you’ve identified the root note as an F, then your guess is that the melody is in F major.

But what if you don’t know if the melody is in major or minor? Don’t give up!

Testing whether your melody is in major or minor

Here’s another trick. Once you’ve discovered the root note, instead of just playing it alone in your left hand, play it along with a major third.

A major third is 4 half-steps to the right of a note. A half-step is the distance from a white key to a black key (or between two white keys without a black key in between).

For example, here is the major third for F:

Play these two notes together with your left hand as you play the melody with your right hand.

Does this combination sound “right”? If so, your melody might be in major.

You can test further by replacing the major third with a minor third. A minor third is 3 half-steps to the right of a note.

That means one half-step to the left of the major third. So for F, the minor third is:

Play these two notes together with your left hand as you play the melody with your right.

Does this combination sound “more right” than the major third? If so, the melody might be in minor.

To reiterate, if your root note is F, then this test will help you guess whether your melody is in the key of F major or F minor.

For some melodies, the root chord can clash with some or even most of the melody. A faster and possibly more accurate approach is to just check whether the melody contains the minor 3rd or the major 3rd.

Just note that some popular melodies contain both, so testing by ear can still be important.

Keep in mind that all of these are imperfect tests for a number of reasons. But they can be relatively quick and don’t require a computer.

Using Specialized Software to Find the Key for You

If you don’t already know your scales and keys well, the easiest method to quickly find the key of a song is probably to use specialized software to do it for you.

If you don’t have a DAW (digital audio workstation) yet, there are many popular options such as Studio One, Ableton Live, Logic, etc. For an inexpensive but powerful option with an unlimited free demo, I recommend Reaper↗(opens in a new tab), which also happens to be the one I use the most.

There are a number of plugins narrowly focused on finding the key of a song, like zplane’s Tonic↗(opens in a new tab) and Antares’ Auto-Key↗(opens in a new tab).

Keep in mind that key detection is not always a simple task. This is because some melodies are ambiguous or use notes outside of the key.

But even in this case, these programs will help you considerably narrow down the possibilities.

Let’s briefly consider Tonic as an example, but there are plenty of resources (including in-depth video tutorials) for each of these options.

Find the key with zplane’s Tonic

In your DAW, either import an audio file of your melody onto a track, or program it as MIDI.

Depending on your DAW, importing an audio file should be as easy as dragging and dropping it into the DAW window.

Now that you have a track with your audio recording or MIDI of the melody, load up Tonic as a plugin on that track.

If you’re using MIDI, you’ll need to make sure that the Tonic plugin comes after the VST instrument plugin on your track.

Once Tonic is loaded, press play on both Tonic and the DAW and Tonic will start analyzing the track in real-time.

Because of the ambiguities and difficulties around key identification mentioned above, Tonic suggests 3 possible keys for the song. In many cases, the main suggestion will probably be correct.

At the bottom of the plugin, there are keys with all the notes in the suggested key, so you can play around with them to check whether it seems like a fit.

Note that if you’re trying to use Tonic to discover the key of an entire song with multiple tracks, you should probably put it on the master bus.

What use is knowing the key?

We’ve explored a few different ways to find the key for a melody. But we haven’t talked about what you can do with that information.

Once you know the key of your song, you’ll be able to narrow down your choices of chords (and notes) that will “sound right”.

Each key corresponds to a scale containing seven notes. For example, the key of C major corresponds to the C major scale. If your song is in C major, then you know the notes in the C major scale will “sound right”.

Each key also corresponds to a set of chords called the chord scale. Elsewhere, I explore the chords in major keys and minor keys in depth. But the important point is that knowing the key also tells you which chords are very likely to “sound right”.

Keep in mind that it’s common in popular music to borrow notes and chords from other scales and keys. So it’s better to think of the key as helping you quickly try out ideas that will work. You can then push the limits of the key from there.