Music Interval Calculator

Enharmonic equivalents are notes that sound identical but are spelled differently: C# and D♭ are the same pitch but different note names. In equal temperament (the tuning system used by virtually all modern instruments), they are exactly the same frequency. The interval calculator lets you select either spelling and correctly identifies the interval name based on the note letters used — for example, C to E♭ = Minor 3rd (3 letter names apart), while C to D# = Augmented 2nd (only 2 letter names apart), even though both span 3 semitones. In practice for ear training, both sound identical, but the spelling matters for music theory, composition, and reading sheet music correctly.

The tritone (augmented 4th or diminished 5th) divides the octave exactly in half — 6 semitones. It has the most dissonant, unstable sound of all intervals in Western tonal music, creating strong tension that demands resolution. Medieval church music theorists called it "diabolus in musica" (the devil in music) and its use was discouraged or forbidden in sacred polyphony. In modern music, it is essential: the dominant 7th chord (e.g., G7 in C major) contains a tritone between its 3rd (B) and 7th (F) that drives the powerful resolution to the tonic chord. Jazz heavily exploits tritone substitution as a harmonic technique.

A harmonic interval is when both notes are played simultaneously (like a piano chord). A melodic interval is when the notes are played one after another (like a melody). The sound quality of the same interval differs between these two contexts: harmonic minor 2nds (e.g., C and C# played together) sound particularly harsh and abrasive, while melodic minor 2nds (a half-step melody move) sound smooth and stepwise. The ear training mode in this calculator trains both types separately — you can set it to harmonic-only, melodic-only, or mixed to match your specific training goal (instrument-specific: pianists often need harmonic recognition; melodic recognition is more universal).

With daily practice (10–15 minutes), most musicians can reliably identify the 5 most common intervals (P4, P5, M3, m3, Octave) within 3–5 weeks. Extending to all 13 intervals typically takes 3–6 months. The final milestone — instantaneous recognition of all intervals in both melodic and harmonic context, ascending and descending, in any key — generally takes 6–18 months. The song mnemonic method accelerates the early stages; later, the goal is to internalize the sound directly without needing the mnemonic cue. Use the trainer's "blind mnemonic" setting to practice without the hint once you feel confident.