Musical intervals are distances between pitches. Melodies move through them, chords combine them, and scales follow their patterns. A complete name joins a number with a quality, so C to E is a major third.
Learning what pitch means in music gives you the starting point; intervals describe the relationship between two pitches. Count note letters and semitones to identify them reliably.
What Is a Musical Interval?
A musical interval is the distance from one pitch to another. The pitches may sound successively or together, and the second may be higher, lower, or identical.
Melodic and harmonic intervals
A melodic interval occurs when two pitches sound successively. It can ascend, descend, or remain on the same pitch.
A harmonic interval occurs when pitches sound simultaneously, forming chords and creating consonance or tension.
An interval between two identical pitches is a perfect unison. The distance from a note to the next note with the same letter name is usually a perfect octave. For a closer look at that 2:1 frequency relationship, see this explanation of octaves.
Why intervals matter
Intervals give music its shape. Seconds create stepwise movement, while sixths and octaves create larger leaps. A major triad has a major third above its root, followed by a minor third. Intervals also support notation, transposition, tuning, harmony, and ear training.
What Are the Names of Musical Intervals?
An interval name has two parts: its number describes the letter distance, and its quality describes its exact size. A third can be major, minor, augmented, or diminished.
Interval numbers
Count letter names inclusively. C to E is C–D–E, making a third. C to G is C–D–E–F–G, making a fifth.
The number does not come from counting keys, frets, or semitones. The chromatic scale and its 12 pitches helps you count semitones after establishing the letter distance.
Interval qualities
Unisons, fourths, fifths, and octaves use perfect quality. Seconds, thirds, sixths, and sevenths use major or minor quality.
- Lower a major interval by one semitone and it becomes minor.
- Raise a perfect or major interval by one semitone and it becomes augmented.
- Lower a perfect or minor interval by one semitone and it becomes diminished.
- Perfect intervals do not have major or minor forms.
Complete interval chart
| Semitones | Common simple interval | Example |
|---|---|---|
| 0 | Perfect unison | C–C |
| 1 | Minor second | C–D♭ |
| 2 | Major second | C–D |
| 3 | Minor third | C–E♭ |
| 4 | Major third | C–E |
| 5 | Perfect fourth | C–F |
| 6 | Augmented fourth or diminished fifth | C–F♯ or C–G♭ |
| 7 | Perfect fifth | C–G |
| 8 | Minor sixth | C–A♭ |
| 9 | Major sixth | C–A |
| 10 | Minor seventh | C–B♭ |
| 11 | Major seventh | C–B |
| 12 | Perfect octave | C–C |
The chart shows common spellings. Three semitones can instead be an augmented second when written C–D♯.
How Do You Identify a Musical Interval?
Identify an interval in three steps: count the letters, count the semitones, and combine the number with its quality. Find the number first because semitone count alone cannot preserve spelling.
Step 1: Count the letters inclusively
For E to G, count E–F–G. The interval number is three, so the answer must be some kind of third.
Step 2: Count the semitones
E to F is one semitone; F to F♯ and F♯ to G add two more. A three-semitone third is minor, making E–G a minor third. A major third interval spans four semitones.
Step 3: Combine number and quality
Use both results to give the complete name:
| Notes | Letter count | Semitones | Correct name |
| C–E | 3 | 4 | Major third |
| E–G | 3 | 3 | Minor third |
| C–F♯ | 4 | 6 | Augmented fourth |
| C–G♭ | 5 | 6 | Diminished fifth |
Why Can the Same Number of Semitones Have Different Names?
Equal-tempered intervals can sound alike but have different names because their written letters and functions differ. C–F♯ is a fourth, while C–G♭ is a fifth, though both span six semitones.
Enharmonic intervals preserve musical meaning
Enharmonic notes sound alike in 12-tone equal temperament but use different spellings. F♯ functions as a raised F, while G♭ functions as a lowered G. The notation shows how the pitch relates to its musical context.
Calling every six-semitone interval a “tritone” is acoustically useful but theoretically incomplete. The same principle applies elsewhere: C–E♭ is a minor third spanning three semitones, whereas C–D♯ is an augmented second.
What Are Simple, Compound, and Inverted Intervals?
Simple intervals fit within one octave. Compound intervals exceed an octave. Inversion moves one note across an octave so the notes exchange positions.
Simple and compound intervals
A ninth is a compound second, a tenth is a compound third, and a twelfth is a compound fifth. To find the corresponding simple interval, subtract seven from the compound number: 10 − 7 = 3, so a tenth reduces to a third.
A major tenth reduces to a major third; a perfect twelfth reduces to a perfect fifth.
How interval inversion works
Simple interval numbers and their inversions add to nine. Qualities change in a regular way:
| Original | Inversion | Quality change |
| Unison | Octave | Perfect remains perfect |
| Second | Seventh | Major and minor exchange |
| Third | Sixth | Major and minor exchange |
| Fourth | Fifth | Perfect remains perfect |
| Augmented | Diminished | The qualities exchange |
C up to E is a major third. Move C above E and E up to C becomes a minor sixth: 3 + 6 = 9, and major changes to minor. Compare the related perfect fourth interval with its fifth inversion.
How Do Musical Intervals Create Melodies and Chords?
Successive intervals create melodic contour; simultaneous intervals create chord structure and degrees of stability or tension.
Intervals in melodies
Stepwise motion uses mostly seconds. Leaps use thirds or larger intervals. An ascending and descending fifth have the same size but create different movement.
Intervals in chords
A major triad stacks a major third and minor third. A minor triad reverses that order.
Unisons, octaves, and perfect fifths generally sound stable, while seconds and sevenths sound tenser. Rhythm, tuning, voicing, style, and context still shape the effect.
How Can You Recognize Intervals by Ear?
Compare two pitches, name their distance, and verify the answer. Practise melodic and harmonic forms separately.
Start with contrasting intervals
Begin with unison, octave, perfect fifth, and minor second. Then compare minor versus major thirds and sixths.
Use familiar melodies as initial cues, then hear each interval across different keys, registers, and instruments.
Follow a short practice routine
- Play or sing a reference pitch.
- Hear a second pitch melodically, then identify its direction.
- Estimate the interval number before deciding its quality.
- Check the answer by counting letters and semitones.
- Sing the interval back and repeat it from a new starting pitch.
A structured interval ear-training routine prevents reliance on one song association. Broader ear-training exercises connect intervals with scales, chords, and transcription.
Frequently Asked Questions
What is the difference between an interval and a semitone?
An interval is the complete musical distance between two pitches, named with a number and quality. A semitone is the smallest standard step in 12-tone equal temperament and is used to measure an interval’s exact size.
How many musical intervals are there within an octave?
There are 13 semitone distances from 0 through 12, including unison and octave. Enharmonic spellings create additional interval names for the same distances.
Why is C to E called a third instead of a fourth?
C to E is a third because inclusive counting gives C–D–E. Its four-semitone size determines the major quality.
Can two intervals contain the same number of semitones?
Yes. C–F♯ and C–G♭ both span six semitones in equal temperament, but the first is an augmented fourth and the second is a diminished fifth. Letter spelling and musical context determine the correct name.
What is the difference between a major interval and a perfect interval?
Seconds, thirds, sixths, and sevenths can be major or minor. Unisons, fourths, fifths, and octaves use the perfect quality instead; lowering or raising a perfect interval creates a diminished or augmented interval.
How do you identify a musical interval by ear?
Listen for the distance, direction, and quality of the two pitches, then compare the sound with intervals you know. Verify the result by identifying the notes and counting both their letter names and semitones.
Vincent is a pitch detection and vocal analysis writer at OnlinePitchDetector. He focuses on pitch recognition, vocal frequency analysis, singing tools, and real-time audio testing for singers, musicians, producers, and beginners.