Transpose Semitones Calculator
Transpose any musical note up or down by a number of semitones. Shows the resulting note name and octave.
How to use this tool
- Enter note, octave and semitones to shift in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your transposed note and the full breakdown beneath it.
Transpose a note up or down any number of semitones and find the resulting pitch name and octave.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
MIDI number = (octave + 1) × 12 + semitone index of note
Transposed MIDI = MIDIin + steps
Result octave = ⌊transposed MIDI ÷ 12⌋ − 1 | Result note = names[transposed MIDI mod 12]
How it works
This calculator converts a note name and octave to its MIDI number, adds the requested semitone shift, then converts the resulting MIDI number back to a note name and octave. The MIDI standard assigns middle C (C4) the value 60, so the formula uses (octave + 1) × 12 plus the chromatic index of the note name.
Results are accurate for the standard 12-tone equal temperament chromatic scale. Enharmonic equivalents (e.g. C# and Db) are always displayed as sharps, matching the internal names array.
Worked example
- Start with A4. The semitone index of A is 9. MIDI = (4 + 1) × 12 + 9 = 69.
- Shift up 3 semitones: MIDI out = 69 + 3 = 72.
- Result octave = ⌊72 ÷ 12⌋ − 1 = 6 − 1 = 5.
- Result note index = 72 mod 12 = 0 → 'C'.
- Combine: C5, MIDI 72.
Transposed note: C5 | MIDI note: 72
Common mistakes to avoid
- Transposing by 12 semitones and being surprised the octave number changes; this is correct behavior, not an error.
- Entering positive steps when intending to transpose down; use a negative value to go down in pitch.
- Transposing only the chord root without transposing all other chord tones by the same interval, producing a mismatched harmony.
Key terms
- Semitone
- The smallest interval in standard Western music; the distance between any two adjacent keys (including black keys) on a piano keyboard.
- MIDI note number
- An integer 0–127 identifying a specific pitch in the MIDI standard. Middle C (C4) = 60; each semitone step equals ±1.
- Octave
- A frequency ratio of 2:1 spanning 12 semitones. The octave number increases by 1 each time the note name C is passed ascending.
- Transposition
- Shifting every pitch in a piece (or a single note) by the same interval, preserving the melodic and harmonic relationships.
- Enharmonic equivalent
- Two note names that represent the same pitch, e.g. C# and D♭. This calculator always returns the sharp spelling.
Frequently asked questions
- How many semitones is a perfect fifth?
- A perfect fifth is 7 semitones (e.g., C to G, or A to E).