Free online tool
Interval Calculator
Interval calculator: pick two notes to get the interval name, semitones and inversion, or add an interval to a note. Hear it, see it, print the table.
On the staff and the keyboard
Interval reference table
Every interval up to the octave, the augmented and diminished spellings, and the compound intervals up to the fifteenth. Examples start on C4 (middle C).
| Short name | Name | Semitones | Example from C |
|---|---|---|---|
| Simple intervals up to the octave | |||
| P1 | perfect unison | 0 | C4–C4 |
| m2 | minor second | 1 | C4–Db4 |
| M2 | major second | 2 | C4–D4 |
| m3 | minor third | 3 | C4–Eb4 |
| M3 | major third | 4 | C4–E4 |
| P4 | perfect fourth | 5 | C4–F4 |
| A4 | augmented fourth | 6 | C4–F#4 |
| d5 | diminished fifth | 6 | C4–Gb4 |
| P5 | perfect fifth | 7 | C4–G4 |
| m6 | minor sixth | 8 | C4–Ab4 |
| M6 | major sixth | 9 | C4–A4 |
| m7 | minor seventh | 10 | C4–Bb4 |
| M7 | major seventh | 11 | C4–B4 |
| P8 | perfect octave | 12 | C4–C5 |
| Augmented and diminished intervals | |||
| A1 | augmented unison | 1 | C4–C#4 |
| d2 | diminished second | 0 | C4–Dbb4 |
| d3 | diminished third | 2 | C4–Ebb4 |
| A2 | augmented second | 3 | C4–D#4 |
| d4 | diminished fourth | 4 | C4–Fb4 |
| A3 | augmented third | 5 | C4–E#4 |
| d6 | diminished sixth | 7 | C4–Abb4 |
| A5 | augmented fifth | 8 | C4–G#4 |
| d7 | diminished seventh | 9 | C4–Bbb4 |
| A6 | augmented sixth | 10 | C4–A#4 |
| d8 | diminished octave | 11 | C4–Cb5 |
| A7 | augmented seventh | 12 | C4–B#4 |
| Compound intervals up to the fifteenth | |||
| m9 | minor ninth | 13 | C4–Db5 |
| M9 | major ninth | 14 | C4–D5 |
| m10 | minor tenth | 15 | C4–Eb5 |
| M10 | major tenth | 16 | C4–E5 |
| P11 | perfect eleventh | 17 | C4–F5 |
| A11 | augmented eleventh | 18 | C4–F#5 |
| d12 | diminished twelfth | 18 | C4–Gb5 |
| P12 | perfect twelfth | 19 | C4–G5 |
| m13 | minor thirteenth | 20 | C4–Ab5 |
| M13 | major thirteenth | 21 | C4–A5 |
| m14 | minor fourteenth | 22 | C4–Bb5 |
| M14 | major fourteenth | 23 | C4–B5 |
| P15 | perfect fifteenth | 24 | C4–C6 |
About the Interval Calculator
The Interval Calculator finds the interval between two notes. Enter two notes and it names the interval, such as perfect fifth (P5) or augmented fourth (A4), and shows its size in semitones, direction, inversion and frequency ratios. It runs in the web browser, is free, and needs no sign-up. It also works in reverse: give it a starting note and an interval to find the note above or below, or give it a number of semitones to list the interval names of that size. Nothing you enter is uploaded. Use it as an interval identifier for music theory homework, a semitone calculator for checking distances, or a half step calculator for finding the exact gap between two keys.
How to use the Interval Calculator
- The tool starts in the two-notes mode, with Note 1 set to C4 and Note 2 set to G4.
- In the Note 1 group, choose a Letter (C to B), an Accidental (double flat (bb) to double sharp (##)) and an Octave (1 to 7).
- Set Note 2 the same way. To reverse the two notes, press Swap notes.
- Read the result. The heading, such as “Perfect fifth (P5)”, is followed by one sentence and rows labelled Interval, Semitones, Direction, Compound interval, Inversion, Consonant or dissonant, Same sound, other spelling, and the frequency and just-intonation ratios.
- Check the staff and keyboard. If the staff is in the wrong clef, change the Clef drop-down to Treble or Bass.
- Press ▶ Play one after the other to hear note 1 then note 2, or ▶ Play together to hear both at once. Sound starts after your first click.
- To find a note from a starting note, switch to the note plus interval mode. Set the Start note group (Letter, Accidental, Octave), then set the Interval group: Quality, Number (1 to 15) and Direction (Up or Down). The heading reads like “C4 up a perfect fifth (P5) = G4”.
- To list the interval names for one size, switch to the semitones mode and set Number of semitones (0 to 36).
The address bar updates as you change settings, and Copy link copies the current address so you can share the exact setup. The Print button (or Ctrl+P) prints the result, staff and keyboard, then the Interval reference table on separate pages.
How do you find the interval between two notes#
Count the letter names from the lower note to the higher one, including both ends. C to G is a fifth because C, D, E, F and G are five letters. That gives the number. Next, count the semitones (half steps) between the two keys to get the size, then compare that size with the major or perfect size of the same number to get the quality.
One semitone smaller than major is minor. One semitone smaller again is diminished. One semitone larger than major or perfect is augmented. C to F sharp and C to G flat both measure 6 semitones and sound the same on a piano. They are still different intervals: C to F sharp is an augmented fourth, and C to G flat is a diminished fifth. This is why the tool asks for letter names and accidentals rather than only keys.
Direction comes from the letters first. G4 to C4 is descending. For two notes with the same letter, the pitch decides, so C#4 to C4 is a descending augmented unison.
How many semitones are in each interval#
A semitone is one half step: the distance from a key to the next key, black or white. Measured upward from the lower note, the sizes are: minor second 1, major second 2, minor third 3, major third 4, perfect fourth 5, perfect fifth 7, minor sixth 8, major sixth 9, minor seventh 10, major seventh 11 and octave 12.
Augmented and diminished intervals move one step away from these sizes. An augmented fourth and a diminished fifth both have 6 semitones. Compound intervals add 12 semitones for each octave: a major tenth has 16 (a major third of 4 plus 12), and a perfect fifteenth has 24.
Semitones mode works from the other side. For 7 semitones it lists P5 and d6. For 6 it lists A4 and d5, with the rarer AA3 and dd6 shown beneath.