Music Transposition Calculator
Shift a note or key by any number of semitones, up or down, with the interval named.
Interval: perfect 5th up. As a key (ignoring octave): C → G.
Transposing a note shifts it by a fixed number of semitones. Moving C4 up 7 semitones lands on G4 — a perfect fifth — while +12 raises it a full octave to C5 and −12 drops it to C3. The interval between the notes stays constant across the whole passage.
What transposition does
To transpose is to move every note in a melody or chord by the same interval, so the pattern of steps — and therefore the tune — is preserved while the overall pitch rises or falls. Because Western music divides the octave into 12 equal semitones, any shift can be described as a whole number: +7 semitones is a perfect fifth up, −5 is a perfect fourth down, and ±12 is a full octave.
The cleanest way to compute this is to number the notes. Each pitch maps to a MIDI-style integer where middle C (C4) is 60 and every semitone adds 1. Transposing then becomes plain addition: shift the number, then read it back as a note name and octave.
Worked example
Transpose C4 up a perfect fifth (+7 semitones).
- 1 Number the starting note. Use n = 12·(octave + 1) + pitch class, with C = 0 … B = 11. For C4: 12·(4 + 1) + 0 = 60.
- 2 Add the semitone shift. A perfect fifth up is +7, so 60 + 7 = 67.
- 3 Find the new pitch class. 67 mod 12 = 7, and pitch class 7 is G. For a downward shift, use ((n mod 12) + 12) mod 12 so the result stays 0–11.
- 4 Find the new octave. ⌊67 ÷ 12⌋ − 1 = 4, so the note is G4.
- 5 Name the interval (optional). A shift of 7 semitones is a perfect fifth, confirming C4 → G4.
Common semitone shifts
Positive shifts move up in pitch; negative shifts move down.
| Shift | Interval | Example (from C4) |
|---|---|---|
| +2 | major 2nd (whole tone) up | C4 → D4 |
| +7 | perfect 5th up | C4 → G4 |
| +12 | octave up | C4 → C5 |
| −5 | perfect 4th down | C4 → G3 |
| −12 | octave down | C4 → C3 |
Transposing for capos and instruments
A guitar capo raises every open string by the fret it clamps, so a capo on fret 3 transposes the sounding pitch up 3 semitones: shapes fingered in C now sound in E♭. To keep the same sounding key while using easier shapes, transpose your chord chart down by the capo fret and play from there.
Transposing instruments work the same way. A part written for a B♭ trumpet sounds a major 2nd (2 semitones) lower than written, so to convert a concert-pitch line into the trumpet part you shift it up 2 semitones. This calculator spells every accidental with sharps; the result is the correct pitch, but the enharmonic spelling a score would use can differ — for example, a shift may produce A♯ where the key signature calls for B♭. Choose the spelling that matches the target key.