Music Interval Calculator - Identify Note and Pitch Intervals

A music interval calculator names the distance between two notes, whether you are reading two piano keys, two fretboard notes, or two spelled note names, and reports the interval quality, semitone count, and frequency ratio.

• • Naming intervals for music theory homework: Pick two spelled notes, switch to note mode when accidentals appear, and read the full interval name including augmented or diminished qualities.
• • Comparing two piano keys or fretboard notes: Stay in pitch mode and the calculator reports the actual sound distance, so C# to C is one semitone and C# to Db is the same key, with a simple interval name.
• • Reading frequency and ratio data for arrangement decisions: Compare just-intonation ratios for perfect fourths, fifths, and octaves against the equal-tempered frequencies the calculator outputs in Hertz.
• • Building chord and scale vocabulary: Use the short symbol (P5, M3, m7) to describe chord stacks and keep the naming consistent across a score.

The calculator covers the twelve pitch classes from C through B, the seven octaves from C0 through B8 in scientific pitch notation, and intervals from unison through two octaves plus a fourth.

When the question shifts from naming the interval to estimating how long the piece plays, the music duration calculator turns the time signature, BPM, and measure count into minutes and mm:ss.

The calculator converts each note to a MIDI note number, takes the difference, and looks it up in a twelve-step interval table to get the interval name, quality, and semitone count. Frequencies come from the same MIDI number using concert pitch A4 = 440 Hz.

• letter_offset: C=0, D=2, E=4, F=5, G=7, A=9, B=11. Letter position within one octave.
• accidental_offset: Natural=0, Sharp=+1, Flat=-1. In pitch mode it picks the sound (C# is one semitone above C); in note mode it also drives the augmented or diminished quality.
• octave: Scientific pitch notation octave from 0 to 8, where C4 is middle C.
• midi: MIDI note number. A4 is 69, every semitone adds 1, every octave adds 12.
• frequency_Hz: Pitch in Hertz. Built from A4 = 440 Hz with equal-tempered tuning where each semitone multiplies by 2^(1/12).

The twelve-step interval table maps semitone counts to interval names and short symbols. Unison, fourth, fifth, and octave use the perfect family. Second, third, sixth, and seventh use the major or minor family. Six semitones is the tritone, an augmented fourth or a diminished fifth. In note mode the letter distance decides which name applies, so C to C# becomes an augmented unison while C to Db becomes a minor second.

According to ISO 16:1975 (Acoustics — Standard tuning frequency), the frequency for the note A in the treble stave shall be 440 Hz, which is the value the calculator uses for A4 in the frequency formula.

Once the interval table makes sense, the chord transposer applies the same semitone math across a chord progression to keep chord qualities intact while shifting keys.

Four short ideas explain every interval the music interval calculator reports and how the numbers get built.

Compound intervals between one and two octaves add seven to the underlying number. A major second plus an octave is a major ninth.

For wave math from a wavelength or period, the frequency calculator applies the same Hertz formula across light, sound, and radio.

Five short steps cover both modes.

1. 1 Pick the mode that matches your question: Between pitches for piano or fretboard sounds with a simple name. Between notes for spelled note names with augmented or diminished qualities.
2. 2 Pick note 1 letter, accidental, and octave: The letter is C through B, the accidental is Natural, Sharp, or Flat, and the octave is the scientific pitch notation number.
3. 3 Pick note 2 letter, accidental, and octave: Note 2 can sit above or below note 1; the absolute distance keeps the result positive.
4. 4 Read the interval name, symbol, and semitone count: The results panel reports the full interval name, the short symbol like P5 or M3, the semitone count, tone count, both frequencies, and the ratio.
5. 5 Switch modes or change octaves to compare spellings: Try the same pair with Natural, Sharp, and Flat in note mode. Move up an octave to grow a simple interval into a compound interval.

For C4 to G4, leave both accidentals on Natural, read Perfect fifth with the P5 symbol, 7 semitones, 3.50 tones, 261.63 Hz and 392.00 Hz, and a 1.4983 ratio.

A purpose-built music interval calculator keeps the MIDI math, the interval table, and the frequency formula in one place.

• • Names every common interval between two notes: Covers unison through two octaves plus a fourth with perfect, major, minor, augmented, diminished, and tritone qualities.
• • Reports the short symbol alongside the full name: Outputs P5, M3, m6, TT, and similar symbols.
• • Shows semitones, tones, and frequencies together: Reads the semitone count, tone count, both pitches in Hertz, and the ratio in one view.
• • Switches between pitch mode and note mode: Pitch mode honors the accidental with a simple name. Note mode adds the spelling for augmented or diminished names.
• • Uses the 440 Hz concert-pitch reference: Frequencies are computed from A4 = 440 Hz with equal-tempered tuning, matching the MIDI standard.
• • Covers compound intervals past one octave: Intervals above twelve semitones are reported as ninths, tenths, elevenths, and beyond.

For the underlying wave math, the harmonic wave equation calculator plots y(x,t) = A sin(kx - omega t + phi), the same waveform that produces a sustained note.

Three choices shape the interval you read, and three caveats tell you when the calculator is used at the edge of its design range.

• • The calculator assumes equal temperament. Just-intonation ratios such as the 3:2 perfect fifth show the small detuning from the equal-tempered ratio of 1.4983.
• • Microtonal intervals between standard semitones are not supported. Quarter tones fall outside the twelve-step interval table.

When a piece changes key mid-flow, the calculator reports a single interval between two notes and does not track key context.

Read the frequency ratio alongside the interval name to see how close the equal-tempered result is to the just-intonation target. The octave is exact at 2.0000, the perfect fifth is 0.0017 below 3:2.

According to the Open Music Theory chapter on equal divisions of the octave, twelve-tone equal temperament splits the octave into twelve equal semitones, so the equal-tempered perfect fifth lands at 2^(7/12) ≈ 1.4983 while the just-intonation perfect fifth keeps the simple 3:2 ratio of exactly 1.5000.

According to the Open Music Theory chapter on intervals, the basic interval qualities are perfect, major, minor, augmented, and diminished. Unisons, fourths, fifths, and octaves belong to the perfect family, while seconds, thirds, sixths, and sevenths belong to the major and minor family.

When frequency and wavelength combine into the speed of sound, the wave speed calculator solves speed = frequency times wavelength for any medium.