Work out the musical interval between any two notes. Choose Between notes to get the full music-theory name (major, minor, perfect, augmented, or diminished) based on how the notes are spelled, Between pitches to name the interval purely by the number of semitones, or Build an interval to find the note a chosen interval above or below a starting note.
The music interval calculator is a complete tool for working with intervals — the building blocks of melody and harmony. An interval is simply the distance in pitch between two notes, and naming it correctly is one of the first skills every musician, composer, and music-theory student needs. This calculator does the work for you three ways: it names the interval between two written notes using full music-theory rules, it names the interval between two pitches by counting semitones, and it can build an interval by finding the note a chosen distance above or below a starting note.
Whether you are analyzing a score, transposing a melody, constructing a chord, or studying for a theory exam, understanding intervals unlocks how music fits together. Below, you will find clear explanations of what intervals are, how they are named, the difference between the calculator's modes, worked examples you can reproduce, and answers to the most common questions.
A musical interval is the difference in pitch between two notes. It has two parts to its name: a quality (perfect, major, minor, augmented, or diminished) and a number (unison, second, third, fourth, and so on). Put them together and you get names like "perfect fifth," "major third," or "minor seventh." The number tells you how many letter names the interval spans, and the quality fine-tunes the exact size.
Intervals can be melodic, where the two notes are played one after the other, or harmonic, where they sound at the same time. Either way, the interval between them is the same. Intervals are also the raw material of everything larger: stack a major third on top of a root, add a minor third above that, and you have a major triad. Learn intervals well, and chords, scales, and harmony all become far easier to understand.
To name an interval, you work out two things.
The number comes from counting letter names from the lower note to the higher note, including both ends. From C to G, you count C (1), D (2), E (3), F (4), G (5) — five letter names — so it is some kind of fifth. From F to C, you count F (1), G (2), A (3), B (4), C (5), again a fifth. The number ignores sharps and flats; it depends only on the letter names.
The quality depends on the exact number of semitones. Interval numbers fall into two families:
So a fifth that spans seven semitones is perfect; widen it to eight semitones and it becomes augmented; narrow it to six semitones and it becomes diminished. A third of four semitones is major; drop it to three semitones and it is minor.
Every interval up to an octave can be measured in semitones (half steps). Here is the standard chart the calculator uses:
Intervals larger than an octave are called compound intervals. A ninth is an octave plus a second, a tenth is an octave plus a third, and so on. The calculator handles these automatically, naming them as ninths, elevenths, twelfths, and beyond.
This mode names the interval the way a musician reading a score would. It looks at how the two notes are spelled — the letter names and their accidentals — and applies full theory rules, producing augmented and diminished intervals where they belong. This is why C to F♯ and C to G♭ get different names in this mode even though they sound identical.
This mode cares only about the sound. It counts the semitones between the two pitches and gives the simplest interval name for that distance. Enharmonic notes — notes that sound the same but are written differently, like C♯ and D♭ — produce the same interval here. A six-semitone gap is simply called a tritone.
This mode works in reverse. Choose a starting note and an interval, pick a direction (above or below), and the calculator tells you the target note with the correct spelling. It is perfect for transposing, building chords, or writing exercises — for instance, a major third above C is E, and a perfect fifth above C is G.
Take the default in the Between notes tab: from C to G. Counting letter names gives C, D, E, F, G — a fifth. The gap is seven semitones, which is the perfect size for a fifth, so the interval is a perfect fifth. Its frequency ratio in equal temperament is 2^(7/12) ≈ 1.4983, and it measures 700 cents. Press Calculate to see the full breakdown, then try your own notes.
The calculator reports several ways of measuring each interval:
The frequency ratios shown here are for equal temperament, the tuning used by pianos and most modern instruments, where the octave is divided into twelve equal semitones. Older just intonation systems use small whole-number ratios (a perfect fifth as 3:2, a major third as 5:4) that differ slightly from the equal-tempered values.
One of the trickiest ideas for beginners is that two intervals can sound identical yet have different names. C to F♯ and C to G♭ both span six semitones and sound the same on a piano, but:
This distinction is not mere pedantry: the way an interval is spelled tells you how it functions in the music and how it wants to resolve. The Between notes mode captures this, while the Between pitches mode ignores it and simply calls both a tritone.
The same idea explains rarer names such as the diminished second (for example, C♯ up to D♭), which spans two letter names yet zero semitones, or the augmented second (such as C to D♯), which spans two letter names and three semitones and sounds identical to a minor third. Composers choose one spelling over another to make the music easier to read and to show a note's harmonic role, and the calculator faithfully reflects whichever spelling you pick.
Throughout this page the terms semitone and half step mean exactly the same thing: the smallest interval in standard Western music, the distance from one key on a piano to the very next key, black or white. Two semitones make a whole tone (or whole step). British and American theory sometimes prefer different words — "tone and semitone" versus "whole step and half step" — but they describe identical distances. Counting in semitones is the most reliable way to measure any interval, which is why the calculator reports every result in semitones alongside its formal interval name, giving you both the precise measurement and the traditional label at a glance.
Each interval has a characteristic sound, and learning to recognize them by ear is a cornerstone of musicianship. Many people memorize intervals using the opening notes of familiar songs:
Intervals are also classified as consonant (stable and pleasant, such as thirds, fifths, and sixths) or dissonant (tense and wanting to resolve, such as seconds, sevenths, and the tritone). Composers use the pull between consonance and dissonance to create tension and release, which is the emotional engine of most music.
When you flip an interval — moving the lower note up an octave so it becomes the higher note — you get its inversion. There is a neat rule: the two interval numbers always add up to nine, and the qualities swap in a predictable way. Major becomes minor, minor becomes major, augmented becomes diminished, diminished becomes augmented, and perfect stays perfect. So a major third (four semitones) inverts to a minor sixth (eight semitones), and a perfect fifth inverts to a perfect fourth. Understanding inversions helps enormously with voice leading and recognizing intervals quickly, and it explains why certain pairs of intervals feel closely related.
The number (second, third, fourth…) counts the letter names spanned, while the quality (perfect, major, minor, augmented, diminished) pinpoints the exact size in semitones. Both together give the full name, such as "minor sixth."
They sound the same but are spelled differently. C to F♯ spans four letter names, making it an augmented fourth, while C to G♭ spans five, making it a diminished fifth. The "Between notes" mode reflects this; the "Between pitches" mode calls both a tritone.
A tritone is any interval of six semitones — three whole tones. It can be written as an augmented fourth or a diminished fifth. Famous for its tense, unresolved sound, it is central to dominant seventh chords and blues.
A perfect fifth is seven semitones. For example, C to G, or A to E. Its equal-tempered frequency ratio is about 1.4983 to 1, very close to the pure 3:2 ratio of just intonation.
A compound interval is larger than an octave, such as a ninth or an eleventh. It equals an octave plus a simple interval — a ninth is an octave plus a second, for instance. The calculator names compound intervals automatically.
Cents are a fine unit of pitch measurement where one equal-tempered semitone is exactly 100 cents and an octave is 1200 cents. They are used to describe very small tuning differences that semitones are too coarse to capture.
This Music Interval Calculator is provided for general educational purposes. Frequency ratios are given for equal temperament and will differ slightly from just intonation or other tuning systems. Interval names in the "Between notes" mode follow standard Western music-theory conventions based on the note spellings you select.