Determine What Key a Song Is In

Learning how to determine what key a song or piece of music is in is a valuable musical skill. Knowing the key allows you to transpose the song (change the key) in order to better suit your voice. It also allows you to experiment with making songs sound different (a great skill for producing an interesting cover of a song). In order to determine the key of a song or piece of music, you will need to understand some basic concepts in music theory. A piano is the simplest instrument to use as an example when explaining and understanding these concepts.

Steps

Getting Acquainted With Some Musical Terms

1. Understand musical steps and musical half steps. Half steps and steps are both intervals, or distances between two notes. They are the building blocks of musical scales.
   • A scale is a group of notes arranged in ascending order. They span an octave, a set of eight notes (from the Latin word octavus, or “eighth”). For example, the major scale in the key of C Major goes C D E F G A B C. The bottom note of a scale is called the “tonic” note.
   • If you imagine the above scale as a ladder, each half step is one rung above the previous. Thus, the distance between B and C is a half step because no other “rungs” come between them. (On a piano, the B and C keys are white keys directly next to each other, without black keys in between.) The distance from C to D, however, is a whole step, because there is an extra “rung” between those notes on the ladder (i.e., the black key on the piano, which represents either C-sharp or D-flat).
   • In the C major scale, the only half steps are between B and C and between E and F. All other intervals are full steps because the C major scale does not include sharp (#) or flat (♭) notes.
2. Understand major scales. The major scale always has the same pattern of whole steps (1) and half steps (½): 1 - 1 - ½ - 1 - 1 - 1 - ½. Thus, the C Major scale is C D E F G A B C.
   • You can create any other major scale by changing your beginning note -- called the “tonic note” -- and following the interval pattern.
3. Understand minor scales. Minor scales are more complicated than major scales and can follow any of several patterns. The most common pattern for minor scales is the Natural minor scale.
   • The Natural minor scale has a pattern of steps and half steps that goes like this: 1 - ½ - 1 - 1 - ½ - 1 - 1.
   • You can transpose this scale pattern (i.e. rewrite it at a different pitch) by starting at a different note and counting up the “rungs” of your scale ladder.
4. Understand musical thirds and musical fifths. Thirds and fifths are types of intervals (distances between notes) that are very common in music. They can be useful in determining what key your music is in. Minor intervals have one less half step than major intervals have, which alters their sound.
   • A third is formed by the first note in the key and the third note in the key. A major third has two whole steps between notes, while a minor third has three half steps.
   • A fifth is formed by the first note in the key and the fifth note in the key. A “perfect” fifth has seven half steps.
   • If you’ve heard the song “Hallelujah” by Leonard Cohen, you’ve heard about intervals, in this line: “It goes like this, the fourth, the fifth, the minor fall, the major lift, the baffled king composing ‘Hallelujah’.” In a lot of pop music (often written in the key of C Major), a very prominent chord progression is the movement from the “fourth” to the “fifth,” which creates a “happy”-sounding movement. In the song, the words “minor fall” are accompanied by a minor chord, and the words “major lift” are accompanied by a major chord.
5. Understand major chords. A basic chord contains three notes, called a triad, arranged in thirds (see Step 4). These chords are usually based on a scale, such as C Major. Major chords have two whole steps between the first and second notes of the triad. A major chord contains a major third and a perfect fifth. The first note of a chord is called the root of the chord.
   • For example, to make a chord based on the C Major scale, you could start at C, the “tonic,” and use it as the “root” of your chord. Then move up to the third of that scale (4 half steps up) to E, then up to the fifth of that scale (3 half steps more up to G). The major chord triad is thus is C - E - G.
6. Understand minor chords. The quality of most chords is determined by the third, or the middle note in the triad. Minor chords have three half steps between the first and second notes of the triad, as opposed to four half steps (or two whole steps) for major chords. A minor chord contains a minor third and a perfect fifth.
   • For example, if you place your fingers up one key from the “root note” of the C Major chord, you will play this chord: D - F - A. This chord is a D minor chord, because the interval between the first and second notes of the chord (D and F) is 3 half steps.
7. Understand diminished and augmented chords. These chords aren’t as common as major or minor chords, but they are sometimes used to create particular effects. Because of their alteration to familiar triads, they create a melancholic, ominous, or spooky feel in music.
   • A diminished chord contains a minor third and a diminished fifth (a fifth that has been lowered a half step). For example, a diminished C chord would look like this: C - E♭ - G♭.
   • An augmented chord contains a major third and an augmented fifth (a fifth that has been raised a half step). For example, an augmented C chord would look like this: C - E - G#.

Reading Music To Find The Key

1. Find the key signature. If you have printed sheet music, you can discover a song’s key by looking at its key signature. This is the set of little markings in between the clef (either treble or bass) and the time signature (the numbers that look like fractions).
   • You will see either # (for sharp notes) or ♭ (for flat notes)
   • If there are neither # nor ♭listed, the song is either in C major or A minor.
2. Read the flats. For key signatures using flats, the key signature is the next-to-last flat (second from the right) marking when read from left to right.
   • When a song has flats marked at B♭, E♭, and A♭, the E♭ is the next-to-last flat marking, and so the piece of music is in the key of E Flat.
   • If there is only one flat, the song is either in D minor or F major.
3. Read the sharps. For key signatures using sharps, the key signature is the note one half-step up from the last sharp marking.
   • When a song has sharps marked at F# and C#, the next note up from the C# is D, and so the piece of music is the key of D.
4. Consult the chord chart. If you play guitar, you will probably refer to chord charts when you learn new music. Many songs begin and end with the chord that matches the key signature. If a piece of music ends with a D chord, it is probably in the key of D.
   • The three basic chords in the key of C Major are C Major (C - E - G), F Major (F - A - C), and G Major (G - B - D). These three chords make up the basis for many pop songs.
5. Learn some scales. Knowing a few of the common scales in the type of music you play will help you figure out what key your song is in. The notes in your chord will all be in the scale.
   • For example, the F Major chord is F - A - C, and all of these notes are in the C Major scale, so the F Major chord is in the key of C.
   • The A Major chord (A - C# - E) is not in the key of C because the C Major scale does not include sharps.
6. Make an educated guess. Most popular music tends to use one of a few common keys because they are the easiest to play on guitar or piano, which are frequently used as instruments for accompaniment.
   • C is by far the most common key for pop songs.
   • Look at the music for the following notes that make up the C Major scale: C - D - E - F - G - A - B – C. Do the notes on the music match the notes in the scale? If the answer is yes, then the song is probably in C.
7. Watch for accidentals. Remember that music occasionally has accidentals, which are notes marked within the music with a ♭, #, or natural sign, even though the key signature does not indicate that note should always take a ♭, #, or natural sign.
   • Accidentals do not change the overall key of the piece.

Finding The Key By Ear

1. Find the tonic note. The tonic, or first note in the scale, will sound right just about anywhere in the song. Using a piano, or your voice, play one note at a time until you find a note that “feels” right with the song.
2. Test the tonic. By playing other notes in the triad you will be able to hear if the chord feels like it fits with the song. Play the fifth note above the note you think is the tonic. The fifth should also sound like it fits in most parts of the song, because it is the second most stable note in a scale.
   • Play the note one half step below your tonic, known as the seventh. You should feel some tension in the context of the song, as if this note is pulling to be resolved into the tonic.
3. Determine if the song is in a major or a minor key. Play the note a major third up from the tonic. If this note fits with the song overall, then it is likely that the tune is in a major key. If not, trying playing a minor third (3♭) and listen to see if this fits better.
   • Practice hearing the difference between a major and a minor triad by playing the following triad: C – E – G is a major triad with C as tonic. Now change the E to E♭. C - E♭- G. Listen to the difference in overall feeling and tone.
   • You may be able to guess whether it is major or minor simply by the feel of the song, because in a lot of western music songs that are keyed in minor feel sad or pensive.
4. Test some chords. The most common chords within a scale should also show up in patterns in the song. One commonly used scale is the G Major scale, which still follows the major scale pattern: G - A - B - C - D - E - F# - G. Its chords are G Major, A Minor, B Minor, C Major, D major, E Minor, and F# Diminished.
   • Songs in the key of G Major will have chords that match these notes.
   • For example, the Green Day song “(Good Riddance) Time of Your Life” begins with a G Major chord (G - B - D), which is followed by a C Major chord (C - E - G). These chords are both in the G Major scale, so the song is in the key of G Major.
5. Sing along with songs. Pay attention to songs that are easy to sing along with for you, versus songs that feel uncomfortably high or low. Note the keys of songs that are easy to sing and songs that are hard for you to sing.
   • Over time you will begin to realize some keys fall easily within your range, while others may be harder for you to reach all the notes. This will help you to make an educated guess about the key before you even begin picking it out on an instrument.
6. Practice your new skill. Make a playlist of some of your favorite songs to sing along to, or use the radio to try to determine the key of the song. You may begin to notice certain patterns. Songs that are in the same key may begin to feel similar to one another to you.
   • Keep a list of songs you've studied, categorizing them by their key.
   • Listen to several songs in the same key in a row to practice getting a feel for that key.
   • Contrast songs in different keys to see if your ear can pick up on the difference.
7. Check your findings. Understanding basic music theory is excellent if you want to write your own songs and adapt others’ songs to your own style, but sometimes you just need a quick key check. There are many mobile apps and websites that can help you find the key of a song.
   • Running a search for the name of the song and the key may bring up the answer for you quickly.
   • When you’re first beginning to learn to find keys by ear it is a good idea to double check that you’re finding the correct answer.

Tips

• There’s a lot of potentially confusing music theory terminology here, but once you practice the scales and chords on a real instrument it will all become clearer.
• Listen to songs for which you know the key, and try to pick out the chords that are in the song. The more you practice and refine your “ear,” the easier it will get for you to discover the key of the song.

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