Music · Theory
Musical interval calculator.
Enter two notes with their octaves to get the interval name, size in semitones and equal-tempered frequency ratio. Or pick a root and an interval and get the note.
Your numbers
Result
Fill the form to see the result.
How do you name a musical interval?
An interval has a number, which counts the letter names it spans (C up to G spans C, D, E, F, G, so it is a fifth), and a quality: perfect, major, minor, augmented or diminished. Unisons, fourths, fifths and octaves can be perfect; seconds, thirds, sixths and sevenths can be major or minor. The size in semitones fixes the quality: a minor third is 3 semitones, a major third 4, a perfect fifth 7 and a tritone 6. In twelve-tone equal temperament n semitones correspond to a frequency ratio of 2n/12.
Worked examples. C4 to G4 is 7 semitones, a perfect fifth, with ratio 27/12 = 1.4983. C4 to F♯4 and C4 to G♭4 are both 6 semitones and sound the same on a keyboard, but the first spans four letters (augmented fourth) and the second five (diminished fifth), so the names differ. The calculator reads the spelling you choose, which is why it asks for note names rather than just semitones. Intervals up to two octaves are supported.
Frequently asked questions
How many semitones are in a perfect fifth?
Seven. A perfect fifth in equal temperament has a frequency ratio of 2^(7/12), about 1.4983.
What is the difference between a major and a minor third?
A major third is 4 semitones and a minor third is 3 semitones.
What is a tritone?
An interval of six semitones, three whole tones. It is called an augmented fourth or a diminished fifth depending on how it is spelled.
Why do C to F sharp and C to G flat have different names?
They sound the same on a keyboard but span a different number of letter names, four versus five, so one is an augmented fourth and the other a diminished fifth.
How do I find a note a major third above E?
Use the second mode: root E, major third, above. The answer is G sharp, since a third above E must be a G.
Sources
Opened
Runs entirely in your browser. Nothing you type is sent or stored.