Transpose by Semitones Calculator: New Note, Octave, Frequency and Chords
Transpose any note up or down by a number of semitones and get the new note name, octave, frequency, interval and cents, plus a whole chord progression transposed in sharps or flats, for capos, key changes and vocal ranges.
How it works
New MIDI = old MIDI + semitones · MIDI = (octave + 1) × 12 + note index (C = 0 … B = 11) · Note = name(MIDI mod 12), octave = ⌊MIDI ÷ 12⌋ − 1 · f = A4 × 2^((MIDI − 69) ÷ 12) · Ratio = 2^(semitones ÷ 12), 1 semitone = 100 cents
Transposing shifts every note by the same number of semitones, so the intervals between notes stay the same and the melody keeps its shape in a new key. Treating each note as a MIDI number makes transposition simple addition: add the semitones, read the name back off the 12-note chromatic circle and recompute the frequency with the equal-temperament formula, where each semitone multiplies the frequency by the twelfth root of 2 (about 1.0595). Type a progression in the chords box and every chord root and slash bass note moves by the same amount, keeping the chord quality (m, 7, maj7, sus4 and so on). Choose sharps or flats for the black keys; flats usually read better in flat keys such as F, B♭ and E♭. A capo works the same way: on the second fret it raises every open string by two semitones. The table lists the starting note moved up and down by up to an octave.
Worked example
With the defaults, A4 (MIDI 69, 440 Hz) moves up 5 semitones, a perfect fourth. The new MIDI number is 74, which is D5, at 440 × 2^(5/12) = 587.33 Hz, a frequency ratio of × 1.3348 (+500 cents). The progression C G Am F becomes F C Dm A♯ (choose flats to read it as B♭).
Sources: Transposition (music) (Wikipedia) · Piano key frequencies and MIDI note numbers (Wikipedia)
Frequently asked questions
How many semitones is a capo on fret N?
Each guitar fret is one semitone, so a capo on the second fret transposes up 2 semitones, the fifth fret up 5, and so on. Enter that number here to see what an open chord shape actually sounds like.
How do I transpose chords to another key?
Count the semitones from the old key to the new one (C to D is +2, C to A is −3 or +9) and move every chord root by that amount, keeping the chord type. Type the chords into the box above to do it in one step.
What does transposing do to the key?
Moving up 2 semitones takes C major to D major, up 5 takes it to F major, and so on. The relationship between notes is unchanged; only the pitch level and the key signature shift.
Will transposing help a singer?
Often, yes. If a song sits too high, transpose it down a few semitones until the highest note lands comfortably in the singer's range; transpose up if it feels too low. The melody keeps its shape either way.
How many semitones are in a tone or an octave?
A whole tone is 2 semitones, a minor third 3, a major third 4, a perfect fourth 5, a perfect fifth 7 and an octave 12. Going up 7 semitones gives the same note name as going down 5, one octave higher.
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This calculator is for educational purposes. Double-check important results before acting on them.