About this tool
An interval is the distance between two notes. Its name consists of a number (third, fifth, sixth …) that follows from the letter names, and a quality (perfect, major, minor, augmented, diminished) that depends on the semitones. That is why C–E (major third) and C–Fb (diminished fourth) are different intervals although both span four semitones. The interval calculator finds the correct name from two notes.
It also shows the semitones, the inversion, the frequency ratio in just intonation (e.g. 3:2 for the fifth) and how far equal temperament deviates from it. With octaves (C4, E5) it recognises compound intervals such as the tenth and descending intervals. The other way round, it finds the note a given interval above or below a note – handy for harmony, ear training and tuning. To break down whole chords, use the Chord Finder.
How it works
- Choose whether to find the interval between two notes or to add an interval to a note.
- Enter the notes (e.g. E and C, or with octaves E4 and C5), or pick the note, interval and direction.
- Read the name, semitones and ratio, and listen to the interval one note after the other or together.
Frequently asked questions
What do short names like M3, P5 or A4 mean?
P stands for perfect, M for major, m for minor, A for augmented and d for diminished; the number is the interval. M3 is the major third, P5 the perfect fifth and A4 the augmented fourth (tritone).
Why is E to C a minor sixth and not a major third?
Without octaves the calculator takes the second note as the next one above. From E up to the next C there are eight semitones and six letter names – a minor sixth. If you add octaves (E4 and C4), it recognises descending intervals too; E4 → C4 is a major third down.
What is the inversion of an interval?
Inverting moves the lower note up an octave. The numbers add up to 9 (third ↔ sixth, fourth ↔ fifth), major becomes minor, augmented becomes diminished and perfect stays perfect. The major third C–E becomes the minor sixth E–C.
What do the just ratio and the deviation show?
In just intonation, intervals with simple frequency ratios sound especially calm: octave 2:1, fifth 3:2, major third 5:4. Pianos and guitars are tuned in equal temperament instead, with every semitone exactly 100 cents. As a result, the major third is about 14 cents sharper than just, while the fifth is only about 2 cents flat.
Which intervals count as consonant?
The calculator calls perfect intervals (unison, fourth, fifth, octave) as well as major and minor thirds and sixths consonant, everything else dissonant. In classical counterpoint the fourth is sometimes treated as a dissonance depending on context.