Relative keys share the exact same key signature but start on different tonics. To find the relative minor of any major key, count down a minor third (or go to scale degree 6); to find the relative major of any minor key, count up a minor third.
Why This Matters for the AP Music Theory Exam
This topic shows up in both the written and aural parts of the AP Music Theory exam. You may need to identify and notate a relative key and its key signature on the written section, which means knowing the order of sharps and flats and where they go on treble and bass clefs. On the aural section, you might hear a passage shift and have to describe whether it moves to a relative minor key or changes mode. You will not be asked to name a key by ear (for example, you would not have to say "F# minor"), but you do need to hear and describe the relationship.
Getting comfortable with relative keys also sets you up for later work on key relationships, modulation, and harmonic analysis, since the relative key is one of the most common keys a passage shifts to.
Key Takeaways
- A relative minor and its relative major share the same key signature but have different tonics.
- To find the relative minor, go down a minor third from the major tonic (or land on scale degree 6 of the major scale).
- To find the relative major, go up a minor third from the minor tonic.
- A minor key uses the same key signature as the major it is relative to, so notate it the same way.
- "Mode" refers to major versus minor; shifting from G major to G minor is a change in mode, not a relative-key shift.
- Always write the natural minor key signature; raised 6th and 7th scale degrees (harmonic and melodic minor) are added as accidentals, not in the signature.
Major and Minor Modes
In music, tonality (key) can shift during a piece, including shifts between major keys and shifts into minor keys. The term mode describes whether a key is major or minor. A major key is in the major mode and a minor key is in the minor mode. There are other types of modes, but those come later in Unit 8.
When a piece shifts from G major to G minor, that is a change in mode, because the tonic stays the same but the quality changes.
On the aural part of the exam, you will not have to name a key by ear or use absolute (perfect) pitch. Instead, you use relative pitch, which musicians build over time. You might hear an excerpt and identify whether a section changes from major to minor. You would not have to say it changes from A major to F# minor by ear alone.
Parallel Keys vs. Relative Keys
These two relationships are easy to mix up, so keep them clearly separated.
Parallel keys share the same tonic but have different key signatures. For example, C major and C minor are parallel because they both center on C. To get the parallel minor from a major key, lower the 3rd, 6th, and 7th scale degrees. Notice that a major key written with sharps can have a parallel minor written with flats. Take D major: lowering the 3rd, 6th, and 7th gives F natural, B flat, and C natural, so D minor has one flat in its key signature.
Relative keys share the same key signature (the same pitches) but have different tonics. For example, C major and A minor are relative keys because they use the same pitches but center on different tonics.
Relative keys sit a minor third apart. The major tonic is a minor third above its relative minor tonic. So the relative minor of C major is A minor, and the two share a key signature with no sharps or flats.
A quick way to remember the direction:
- Major to relative minor: go down a minor third (or move to scale degree 6).
- Minor to relative major: go up a minor third.
Minor Key Signatures
The three forms of the minor scale are natural, harmonic, and melodic minor. They sound different, but they all share the same key signature, which comes from the relative major.
For natural minor, take the key signature from the relative major. If you want C minor, the relative major is E flat major, so the signature has three flats: B flat, E flat, A flat.
You always write the natural minor key signature, even when the music raises the 6th or 7th scale degree. Those raised pitches (which create harmonic and melodic minor) are written as accidentals in the music, not in the key signature. One reason is that it is awkward to mix sharps and flats in a single key signature.
Using the Circle of Fifths for Minor Keys
The circle of fifths works for minor keys too. Start from A minor, which has no sharps or flats.
- Going clockwise: A minor, E minor, B minor, and so on. E minor has one sharp (F#), B minor has two sharps (F# and C#), and the pattern continues.
- Going counterclockwise: A minor, D minor, G minor, and so on. D minor has one flat (B flat), G minor has two flats (B flat and E flat), and the pattern continues.
The order of sharps (F C G D A E B) and the order of flats (B E A D G C F) is the same for major and minor keys, so the placement of accidentals on the staff stays consistent.
How to Use This on the AP Music Theory Exam
Notation
When asked to notate a relative key and its key signature, place the sharps or flats in the correct order and on the correct lines and spaces for the clef you are given. Sloppy or out-of-order accidentals can cost points because the reader cannot tell what key you mean. Practice writing key signatures in both treble and bass clef.
Finding a Relative Key Quickly
- Given a major key, count down a minor third (three half steps) to land on the relative minor tonic. Both keys keep the same signature.
- Given a minor key, count up a minor third to find the relative major.
- Double check by confirming both keys share the same number and type of accidentals.
Aural Recognition
When you hear a shift, decide whether it is a relative-key change (same signature, new tonic, often a brighter to darker feel between relative major and minor) or a change in mode (same tonic, different quality). You are describing the relationship, not naming the exact letter key by ear.
Common Trap
Watch for harmonic and melodic minor. A raised 7th (or raised 6th and 7th) appears as an accidental in the music. Do not add it to the key signature, and do not let it trick you into thinking the passage changed keys.
Common Misconceptions
- Relative and parallel are not the same. Relative keys share a key signature but have different tonics; parallel keys share a tonic but have different key signatures.
- Harmonic and melodic minor do not get their own key signatures. You write the natural minor signature and add raised scale degrees as accidentals.
- A change in mode is not a relative-key shift. Going from G major to G minor keeps the same tonic, so it is a mode change, not a move to the relative key.
- You do not need perfect pitch for the aural section. You only describe relationships like major to relative minor, not exact key names.
- The relative minor is not built on scale degree 1 of the major; it is built on scale degree 6 (a minor third below the major tonic).
Related AP Music Theory Guides
Vocabulary
The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.Term | Definition |
|---|---|
change in mode | A shift between major and minor keys, such as moving from G major to G minor. |
key relationship | The harmonic connection between two keys, such as relative keys, which share the same key signature but different tonics. |
key signature | A grouping of sharps or flats presented in a specific order at the beginning of a musical staff that indicates which pitches belong to a particular major or minor scale. |
major key | A key or tonal center based on a major scale, characterized by a specific pattern of whole and half steps. |
minor key | A key or tonal center based on a minor scale, characterized by a different pattern of whole and half steps than major keys. |
mode | A classification of keys as either major mode or minor mode, indicating whether a piece is in a major or minor key. |
relative key | A key that shares the same key signature as another key but has a different tonic note; for example, D major and B minor are relative keys. |
tonic | The first scale degree and the primary harmonic center of a key, providing the sense of resolution and stability. |
Frequently Asked Questions
What are relative keys in music theory?
Relative keys are a major key and a minor key that share the same key signature but have different tonics. C major and A minor are relative keys because both use no sharps or flats.
What key has 3 flats?
The key signature with three flats is shared by E-flat major and C minor. The three flats are B-flat, E-flat, and A-flat.
How do I find the relative minor of a major key?
Go down a minor third from the major tonic, or find scale degree 6 of the major scale. For example, the relative minor of D major is B minor, and both keys have two sharps.
How do I find the relative major of a minor key?
Go up a minor third from the minor tonic. For example, the relative major of F minor is A-flat major, so both keys use four flats.
What is the difference between relative and parallel keys?
Relative keys share a key signature but have different tonics. Parallel keys share the same tonic but use different key signatures, like C major and C minor.
Do harmonic and melodic minor change the key signature?
No. Minor key signatures are based on natural minor. Raised 6th or 7th scale degrees in harmonic or melodic minor are written as accidentals in the music, not added to the key signature.