What Is a Music Interval? All 13 Intervals Explained with Audio

What Is a Musical Interval?

An interval is the distance in pitch between two notes, measured in semitones.

“C and G,” “A and A,” “E and F” — whenever you compare two notes, you’re describing an interval. Every chord is built from intervals. Every scale is a sequence of intervals. Understanding them is foundational to music theory.

Why Learn Intervals?

Knowing your intervals lets you:

• Understand chord construction: A major chord is root + major third + perfect fifth
• Read and write scales: A major scale is a specific pattern of whole and half steps
• Hear music more accurately: Instead of guessing notes, you think “that’s a minor seventh above the root”
• Transpose fluently: The interval relationships stay the same across all keys

What Is a Semitone?

A semitone (also called a half step) is the smallest interval in standard Western music — the distance between any two adjacent keys on a piano, including black keys.

C to C# = 1 semitone. C to D = 2 semitones (one whole step).

All 13 Intervals

Symbol	Name	Semitones	Example (from C)
P1	Perfect Unison	0	C → C
m2	Minor Second	1	C → Db
M2	Major Second	2	C → D
m3	Minor Third	3	C → Eb
M3	Major Third	4	C → E
P4	Perfect Fourth	5	C → F
A4/d5	Augmented Fourth (Tritone)	6	C → F#
P5	Perfect Fifth	7	C → G
m6	Minor Sixth	8	C → Ab
M6	Major Sixth	9	C → A
m7	Minor Seventh	10	C → Bb
M7	Major Seventh	11	C → B
P8	Perfect Octave	12	C → C (one octave up)

Interval Quality: Perfect, Major, Minor

Intervals use quality descriptors:

Perfect (P) — applies to unisons, fourths, fifths, and octaves. These are the most stable intervals, with the simplest frequency ratios.

Major (M) and Minor (m) — applies to 2nds, 3rds, 6ths, and 7ths. Major intervals are one semitone wider than minor. Major tends to sound brighter; minor tends to sound darker.

Augmented (A) and Diminished (d) — one semitone wider/narrower than perfect or major/minor. The tritone (A4/d5) is the most common example.

Consonance and Dissonance

Intervals are also categorized by how “stable” or “tense” they sound:

Perfect consonances: P1, P5, P8 — the most stable, pure-sounding intervals
Imperfect consonances: m3, M3, m6, M6 — stable but with more color
Dissonances: m2, M2, A4, m7, M7 — tense, unstable, want to resolve

These categories aren’t about “good” vs “bad” — dissonances are essential to musical motion and expression.

Intervals and Chords

The difference between a major and a minor chord is just one semitone — specifically, whether the third is major or minor.

Chord	Third
Major chord (bright)	Major third (4 semitones)
Minor chord (dark)	Minor third (3 semitones)

This single half-step difference is responsible for one of the most emotionally significant distinctions in music.

Try the Interval Calculator

The Interval Calculator on this site lets you pick any two notes and see the interval name, semitone count, and consonance level immediately. Use “Play in sequence” to hear the melodic interval and “Play together” to hear the harmonic version.

Click any row in the interval table to jump directly to that interval — useful for comparing multiple intervals quickly.