In music, the key of a piece establishes the most important notes used in the melody, the most common chord progressions, and the tonal center around which everything revolves. Learning a piece without understanding the key wastes a lot of energy. It would be like reading slang words you are unfamiliar with. You can sound out the words, and get the gist of what they mean, but it’s harder to understand because you don’t have the appropriate context.
There are several methods to find the key of a piece. In this article, we cover determining the key by ear, by key signature, or by chord progressions.
Method 1: Find the Key by Ear
Music is about listening, so finding a key by ear is more intuitive than other methods. First some definitions:
The key of a piece is the set of pitches that a piece revolves around. In this article we will only classify pieces as major or minor even though many other scales exist.
The tonal center of a piece is the single pitch that a piece revolves around.
For example, a piece in the key of A major uses the notes of the A major scale most frequently (A B C♯ D E F♯ G♯). The tonal center is A because it is the most important note. In such a piece chords will resolve or “land on” the A major chord most frequently and A will likely be the most used pitch and often the first or last note of a melody.
To better understand the importance of a tonal center, it helps to listen to music without a tonal center. This music is called atonal music, it is bizarre and not my favorite. Notice how un-grounded, and unsettling it sounds because it has no tonal center.
Now let’s dive into how to learn the key of a song by ear.
Step 1: Determine the Tonal Center
I like the process proposed by Rhythmic Canada (youtube video below) for finding the tonal center. The steps he outlines are:
- Listen to the song. Get a feel for it, maybe listen for the melody.
- hum. This step might feel weird. This forces your brain to pick a note, and often it picks the most important note ie the tonal center.
- find the hummed note on your instrument. Hum while moving up or down chromatically until you have matched the pitch.
Two tips to try if you have trouble finding the tonal center.
- when you hum try moving higher or lower slowly. Does the initial note you picked sound more fitting than the other notes? Experiment by humming just a bit higher and lower, and also substantially higher and lower
- try humming the melody. The tonal center may be the note that appears most frequently, or the note that starts/finishes phrases.
Step 2: Determine If It’s Major or Minor
In general a piece is in a major key if it evokes primarily positive emotions and in a minor key if it evokes primarily negative emotions. A simplification is:
Major = Happy
Minor = Sad
If you are still unsure whether your song is major or minor, you can develop your major/minor recognition skills with this simple major vs minor test on youtube. Or you can read more on the theoretic difference between major and minor.
Step 3: Name the key
Now you can name your key. It will follow the naming system of tonal center followed by major or minor. For example, A major, B minor etc.
You just found the name of your key by ear!
Method 2: How To Find the Key of a Song in Sheet Music
If you read sheet music, identifying the key by the key signature and other context clues will tip you off to the scales and chords likely to be used in the piece (more on that in the chord progressions section).
Where to Find the Key Signature
Pretty simple. The key signature is far to the left at the beginning of the piece. It is a collection of sharps or flats. Below we have 5 flats which corresponds to D♭ major or B♭ minor.
How to identify a key signature
How did we get to D♭ major for the piece above? For each key signature there is a corresponding major and relative minor key; once identified determine whether the piece is major or minor.
If the key uses flats, then the second to last flat is the major key and three half steps below is the minor key.
If the key signature uses sharps, go to the last sharp and move up a half step for the major key and down a whole step for minor key.
The tricky part is deciding whether the piece is major or minor. There is no fail safe method but you can try the following.
- Use your ears. Does it sound angry, sad, or mysterious? Then it’s probably minor. Does it sound happy, contented, or jubilant? Then it’s probably major. Use the skills explained in the “Find the key by ear section.”
- Look to the beginning or end. Often (but not always) the first or last chord suggests the key of the piece. Does the chord correspond to a major key or minor key? In “Clair de Lune” the first notes in the first measure are D♭ F and A♭ which spell a D♭ major chord. Clair de Lune is then in D♭ major.
It can be tricky business. It doesn’t help that composers sometimes like to be ambiguous. I find the beginning of Clair de Lune to be sad even though it is written in a major key. Unusually, the opening of F and A♭ is a minor 3rd which may give the minor sound as it isn’t until then end of the first measure that a D♭ is played.
The piece picks up around 2:04 which is when I begin to hear a more joyful, major sound.
Key Signature Chart
For more help figuring out your key consider the chart of the circle of fifths below. For our purposes we use it as a simple key signature chart. Find the key signature along the outside, and determine if the piece is in minor (shown in green) or major (red).
Method 3: Find the Key From Chord Progressions
This method requires the most musical knowledge, making it a great exercise if you are moving past beginner and into the intermediate or early advanced stages.
To use this method, think of yourself less as a mathematician following a formula and more as a detective looking for clues.
Common Chords of a Key
The most common chords of a key are created from the notes of its scale – these are known as the diatonic chords.
Here are the chords of the D major key.
Often times composers use roman numerals to describe the chords using the following rules.
- Major chord = capitalized roman numeral
- Minor chord = lower case roman numeral
- Diminished chord = lower case roman numeral and a degree sign °
- Diminished chord consists of a root, minor 3rd and diminished 5th.
Often the strongest sense of resolution in a piece happens when a V chord moves to I chord. For example when A (V) moves to D (I) in the example below.
D Bm G A D => I vi IV V I
The V chord is so important that it often remains major even in minor keys. For example, in the charts of the B minor chords below, F# uses A♯ making it major.
Clues for Key of a Chord Progression
When determining the key of a piece, use the following tips.
- List out the chord progression. What key do most of the chords fall into?
- The V chord followed by the I chord is the strongest resolution in music. Are there any places where a potential “V” chord leads to a potential “I” chord?
- What chord is at the beginning or end of musical phrases? Often it is the “I” chord.
- Use your ear again. When playing a chord progression what chord feels like home base. It may take a while and a lot of humming before you develop this sense.
- If you get stumped you could use this key finder by chords tool. Input the chord progressions and a couple notes and see what key signature(s) it spits out. Use this to double check your predictions.
Here is the chord progression to “Brave” by Sara Bareilles. Note that chords are major unless there is a lower case “m” in which case it is minor.
G Em C and D could fit into two keys – G major and E minor. In this case, we are in G major, here are 3 clues I would use to support that.
- The phrase starts and ends on a G chord
- D is the fifth scale degree
- It sounds happy and seriously makes me want to get up and dance.
A more challenging example comes from “Colder Heavens” written by one of my favorite artists – Blanco White. (He seamlessly integrates a smattering of folk influences including Andean, Flamenco, and Celtic) .
Em A and Bm all fit in D major or B minor. So which one is it?
Neither. Instead it is E minor. Why?
- Em constitutes half the chords in this section
- Em is the first and last chord.
- In other sections of the piece the C major chord appears which is part of the E minor key, but not part of the D major or B minor keys.
In my opinion, the A major chord is just added to sweeten the melancholic feel.
Side note: A major is part of the E Dorian key (don’t worry if you don’t know what that means). I argue that this piece is in E minor instead of E Dorian because of the occurrence of C major in other parts of the song. Probably either answer is acceptable.
It may seem challenging at first, but over time finding the key of a piece becomes more and more intuitive. I’d guess that a highly trained musician could use some combination of these methods to determine the key of a piece in about 5 seconds. But don’t feel bad if at first it takes you 1 minute to guess the key of a piece – and then you get it wrong. Certainly you learned in the process.
Moving passed understanding keys you could enrich your understanding by:
- Creating simple chord progressions in a key (say D), try especially using I IV and V chords
- Practice finding the key signature by ear on several of your favorite tunes.
- Look at chord sheets and try to determine the key.