Music · Pitch

Pitch shift and speed calculator.

When audio is sped up or slowed down by varispeed, tape or turntable speed, pitch moves with it. Convert between semitones, percent speed change, cents and frequency ratio.

Semitones ↔ percentFrequency ratio and centsTwo speeds in, pitch out

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Your numbers

Between -36 and +36. Twelve semitones is one octave.
+6 means 6% faster, -6 means 6% slower.
Any unit, as long as both speeds use it: BPM, rpm or ips.
For a record played at 45 instead of 33⅓ rpm, enter 33.3333 and 45.
Shows the new running time at the new speed.

Result

Fill the form to see the result.

How do you convert semitones to a speed percentage?

In twelve-tone equal temperament each semitone multiplies frequency by 21/12, about 1.05946, and an octave (12 semitones) doubles it. When you change playback speed without any time-stretching, pitch and speed change together, so the speed ratio is 2semitones / 12 and the percent change is (ratio − 1) × 100. Going the other way, semitones = 12 × log2(ratio).

Worked examples. One semitone up is a ratio of 1.05946, so +5.95% faster; one semitone down is 0.94387, so −5.61%. The two are not mirror images because percent is measured from the starting speed. A 6% speed-up is 12 × log2(1.06) = +1.01 semitones. Playing a 33⅓ rpm record at 45 rpm is a ratio of 45 ÷ 33.333 = 1.35, which is +35% and about +5.2 semitones (a little over a perfect fourth).

Time-stretch is different. Software time-stretching and pitch-shifting change speed or pitch independently. This calculator applies when pitch and tempo move together, as with varispeed, tape, vinyl or simply playing a file back at a different sample rate. A music player that preserves pitch needs only the percent figure for the tempo.

Frequently asked questions

How many percent is one semitone?

Going up one semitone is a speed ratio of 2^(1/12) = 1.05946, which is +5.95%. Going down one semitone is 0.94387, which is -5.61%.

How do I convert percent speed to semitones?

Semitones = 12 x log2(1 + percent / 100). A 6% speed-up is about 1.01 semitones and a 100% speed-up is 12 semitones, one octave.

What pitch change is 33 1/3 to 45 rpm?

The speed ratio is 45 / 33.333 = 1.35, which is +35% or about +5.2 semitones.

How many cents is a semitone?

100 cents. An octave is 1,200 cents.

Does changing the tempo always change the pitch?

Only when the audio is resampled or played faster or slower as a whole, like tape or vinyl. Time-stretching tools change tempo while keeping pitch, and pitch-shifting tools do the reverse.

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