In AP Music Theory, the subdominant is the fourth scale degree of a major or minor scale and the triad built on it (IV in major, iv in minor). It sits a perfect fifth below the tonic and serves predominant function, typically moving toward the dominant in a harmonic progression.
The subdominant is the name for scale degree 4. In C major, that's F. The name doesn't mean "below the dominant" in the way you might guess. The dominant sits a perfect fifth above the tonic, and the subdominant sits a perfect fifth below it. They're mirror images around the tonic, which is exactly why both chords feel so structurally important.
The term also refers to the chord built on that degree. In major keys it's a major triad (IV); in minor keys it's usually a minor triad (iv). Functionally, the subdominant chord is the classic predominant. It's the chord that says "the dominant is coming." The standard 18th-century progression you'll analyze all year is tonic, then predominant (often IV or ii), then dominant, then back to tonic. Per PIT-1.E.1, you need to know subdominant alongside the other scale degree names (tonic, supertonic, mediant, dominant, submediant, subtonic, leading tone) and be able to identify it by ear and on the page.
The subdominant shows up early and never leaves. In Unit 1 (Topic 1.4), learning objective AP Music Theory 1.4.B asks you to identify the function of a pitch relative to the tonic using scale degree names or numbers in both performed and notated music. "Subdominant" is one of the eight names you have to know cold. In Unit 2 (Topic 2.1), the same scale-degree framework carries into all three forms of the minor scale, where degree 4 stays put while degrees 6 and 7 do the shifting. Then in Unit 5, the subdominant becomes the poster child for predominant function, the harmonic role at the center of AP Music Theory 5.4.A, which asks you to identify and describe harmonic function and progression. If you can't spot the subdominant, you can't explain why a progression like I-IV-V-I works.
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Dominant (Units 1 and 5)
The subdominant and dominant are a matched pair. The dominant is a fifth above the tonic, the subdominant a fifth below. In progressions, the subdominant's whole job is to set up the dominant, which then resolves to tonic. Think of it as a relay race in the order IV to V to I.
Tonic (Unit 1)
Every scale degree name describes a relationship to the tonic, and the subdominant's relationship is a perfect fifth below. When you hear IV resolve directly to I (the "Amen" plagal cadence), you're hearing the subdominant relate to home without the dominant's help.
Cadence (Unit 5)
The plagal cadence (IV-I) is the subdominant's signature move, and IV also appears right before the dominant in authentic cadences. Knowing which chord precedes the cadence is half of harmonic analysis.
Circle of fifths (Unit 1)
Move one step counterclockwise on the circle of fifths from your tonic and you land on the subdominant key (C major's neighbor F major). That's the same fifth-below relationship, drawn as a wheel instead of a scale.
Multiple-choice questions test the subdominant two ways. First, as a label, where a stem asks you to name a scale degree or identify which pitch in a melody is the subdominant, exactly the skill in 1.4.B. Second, as a function, where you analyze a progression and recognize the IV (or iv) chord doing predominant work before a dominant chord. Aural questions can play a progression and ask which chord you heard, so train your ear on the I-IV-V-I sound. Practice questions in this area often pair the subdominant against the leading tone, asking which degree creates tension that resolves to tonic (answer: the leading tone, not the subdominant). No released FRQ has used the word verbatim, but Roman numeral analysis and figured bass realization in the FRQ section absolutely require you to write and resolve IV chords correctly.
Both start with "sub," but they're different degrees. The subdominant is scale degree 4 (a fifth below tonic, mirroring the dominant a fifth above). The submediant is scale degree 6 (a third below tonic, mirroring the mediant a third above). In C major, the subdominant is F and the submediant is A. On a multiple-choice question, mixing these up is the easiest way to lose a point you actually knew.
The subdominant is scale degree 4, located a perfect fifth below the tonic, which mirrors the dominant a fifth above.
The chord built on the subdominant is major in major keys (IV) and minor in minor keys (iv).
The subdominant chord carries predominant function, meaning it typically leads to the dominant in progressions like I-IV-V-I.
A IV chord moving directly to I creates a plagal cadence, the "Amen" sound at the end of hymns.
Unlike the leading tone, the subdominant does not create strong tension that demands resolution to tonic; it builds motion toward the dominant instead.
Don't confuse the subdominant (degree 4) with the submediant (degree 6); the "sub" names describe intervals below the tonic, not positions below other degrees.
The subdominant is the fourth scale degree and the chord built on it (IV in major, iv in minor). It sits a perfect fifth below the tonic and functions as a predominant chord, typically moving to the dominant.
Not exactly, and this trips people up. The name means it's a dominant-distance (a perfect fifth) below the tonic, mirroring how the dominant is a fifth above. It does happen to sit one step below scale degree 5, but the fifth-below-tonic relationship is the real logic.
The subdominant is scale degree 4 and the submediant is scale degree 6. In C major, the subdominant is F and the submediant is A. Both names use "sub" because they mirror the dominant and mediant below the tonic.
No. The leading tone (degree 7) is the unstable degree that pulls strongly to tonic, and that's a favorite multiple-choice distinction. The subdominant is more stable on its own; its tension is harmonic, pushing the progression toward the dominant rather than resolving by half step.
In natural minor, the subdominant triad is minor (iv). When the melodic minor scale raises scale degree 6 ascending, the chord built on degree 4 can become major (IV), which is one reason composers use the melodic minor form.