Music Interval Calculator
Find the interval between any two notes. Pick two pitches and the calculator names the interval and counts the semitones, from perfect unison up to compound intervals.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the steps
How the Music Interval Calculator Works
An interval is the distance in pitch between two notes. This calculator lets you pick any two notes (with their octaves) and instantly tells you the interval name, the number of semitones between them, and the interval’s quality (perfect, major, minor, augmented or diminished). It is built for students learning ear training, theory and harmony.
The Formula
Every note has an absolute pitch position. Because there are twelve semitones in an octave, you can give each note a single number:
Absolute pitch = (octave × 12) + pitch-class index
where the pitch-class index runs C = 0, C sharp = 1, D = 2, and so on up to B = 11. The interval is simply the distance between the two pitch numbers:
Semitone distance = | absolute pitch of note 2 − absolute pitch of note 1 |
That semitone count is then matched to the standard interval names. Distances of 0 to 12 cover the simple intervals (unison through octave); larger distances are split into octaves plus a simple interval, giving a compound interval.
Worked Example
Take the notes C4 and G4:
- C4 pitch = (4 × 12) + 0 = 48
- G4 pitch = (4 × 12) + 7 = 55
- Distance = 55 − 48 = 7 semitones
- Seven semitones = a perfect fifth (P5)
Now take C4 and E5:
- Distance = 64 − 48 = 16 semitones
- 16 = one octave (12) + 4 → a major third plus one octave (a major tenth, a compound interval).
Semitones and Interval Names
| Semitones | Interval name | Quality |
|---|---|---|
| 0 | Perfect unison | Perfect |
| 2 | Major 2nd | Major |
| 3 | Minor 3rd | Minor |
| 4 | Major 3rd | Major |
| 5 | Perfect 4th | Perfect |
| 6 | Tritone (A4/d5) | Augmented / diminished |
| 7 | Perfect 5th | Perfect |
| 12 | Perfect octave | Perfect |
Why Intervals Matter
Intervals are the building blocks of melody and harmony. Recognising them by ear lets you transcribe music, and knowing their semitone size lets you transpose a part, build chords and understand why certain note pairs sound consonant or dissonant. Because the calculator works purely from semitone distance, it handles every key and every enharmonic spelling consistently.
Frequently asked questions
How do I find the interval between two notes?+
Count the number of semitones (half steps) between the two notes, then match that number to an interval name. For example, four semitones is a major third and seven semitones is a perfect fifth.
How many semitones is a perfect fifth?+
A perfect fifth spans seven semitones, such as C up to G. A perfect fourth is five semitones and a perfect octave is twelve semitones. The calculator counts these for you automatically.
What is a compound interval?+
A compound interval is larger than one octave. The calculator reports it as the simple interval plus the number of octaves, for example a major third plus one octave (a major tenth) is sixteen semitones.
Does the calculator handle sharps and flats?+
Yes. Enharmonic notes such as C sharp and D flat share the same pitch, so they have the same semitone count. The tool names the interval by its size in semitones rather than its written spelling.
What does the tritone mean in the results?+
A tritone is the interval of six semitones, exactly half an octave. It can be written as an augmented fourth or a diminished fifth, which is why the calculator labels its quality as augmented or diminished.