Count the letters for the number
Include both endpoints. C to E spans C–D–E, so it is some kind of third. C to F spans four letter names, so it is some kind of fourth.
Intervals are
musical distance.
Count the letters. Hear the distance.Learn how interval number comes from letter names and quality comes from semitones. Then practice by sight, by ear, or in a mixed round.
Count semitones for the quality
Compare the sound to the interval’s major or perfect form. C–E is a major third (4 semitones); C–E♭ is a minor third (3). Perfect intervals use P; major/minor intervals use M or m.
The tritone has two spellings
A tritone spans six semitones. Written as C–F♯ it is an augmented fourth (A4); written as C–G♭ it is a diminished fifth (d5). The sound is the same on a piano, but the notation tells you which interval to name.
Spellings carry the meaning
C–F♯ is an augmented fourth and C–G♭ is a diminished fifth. They share a piano key, but the letter count gives different interval numbers. Keep enharmonic spelling intact.
QUICK REFERENCE
Simple intervals
Semitone count is measured from the lower note. Enharmonic spellings can change the interval quality even when the piano keys match.
| Interval | Semitones | Letter span |
|---|---|---|
| Perfect unison (P1) | 0 | 1 |
| Minor / major second (m2 / M2) | 1 / 2 | 2 |
| Minor / major third (m3 / M3) | 3 / 4 | 3 |
| Perfect fourth (P4) | 5 | 4 |
| Tritone: augmented fourth / diminished fifth (A4 / d5) | 6 | 4 / 5 |
| Perfect fifth (P5) | 7 | 5 |
| Minor / major sixth (m6 / M6) | 8 / 9 | 6 |
| Minor / major seventh (m7 / M7) | 10 / 11 | 7 |
| Perfect octave (P8) | 12 | 8 |
GENERATED PRACTICE
Name that interval.
Choose a difficulty and mode, then generate a fresh example.
MIXED PRACTICE
—
Listen to both notes on piano.
For advanced and expert practice, compound intervals and enharmonic spellings may appear. Count the note letters first; use the sound to confirm the semitone distance.
READY TO MIX TOPICS?
Put intervals beside the rest of your theory.
Custom tests shuffle question types from every topic you select, so interval naming can appear alongside chord spelling, scales, cadences, voice leading, secondary dominants, and melodic dictation.
Build a mixed test ↗