About the Pitch Shift & Speed Calculator
When you speed a recording up or slow it down without time-stretching — on a turntable, a tape machine, a sampler or a DAW’s varispeed mode — its pitch moves too. This calculator converts between the two: enter a speed change in percent to see how many semitones and cents the pitch moves, or enter a pitch shift in semitones and cents to get the exact playback speed you need.
It is useful for DJs nudging a record with the pitch fader, producers re-pitching samples to fit a key, transcribers slowing a solo down, and anyone working out why a 33⅓ rpm record played at 45 rpm jumps up by more than a perfect fourth. It also shows what happens to the song’s tempo, its running time and a reference note such as A440.
The math assumes plain resampling, where speed and pitch change together by the same ratio. Time-stretching and pitch-shifting plug-ins can separate the two, in which case use the semitone value alone.
With the default inputs, the pitch shift is 1.009 semitones. Change any value above to recalculate instantly.
How to use the pitch shift & speed calculator
- 1Choose whether you know the speed change or the pitch change you want.
- 2Enter the speed change in percent, or the semitones and extra cents.
- 3Add the original tempo and running time to see how they change.
- 4Optionally enter a reference note frequency, such as A440, to see where it lands.
- 5Use the reference table to find the speed for any whole-semitone shift.
Formula and method
Equal temperament divides every octave (a doubling of frequency) into 12 equal semitones, so one semitone is a frequency ratio of 2^(1/12) ≈ 1.05946. When audio is resampled, every frequency in it is multiplied by the speed ratio r, so the pitch shift in semitones is 12 × log₂(r) and in cents is 1,200 × log₂(r).
Going the other way, the speed needed for a shift of n semitones is r = 2^(n/12). Tempo is multiplied by r and running time is divided by r. Because the relationship is logarithmic, +6% is about +1 semitone but −6% is slightly more than −1 semitone.
- r
- Speed ratio (new speed ÷ original speed; 1.06 = 6% faster)
- semitones
- Pitch change in equal-tempered half steps
- cents
- Pitch change in hundredths of a semitone
Worked examples
DJ pitch fader at +6%
A +6% speed change is a ratio of 1.06, and 12 × log₂(1.06) = 1.009 semitones — almost exactly one half step up. A 120 BPM, 3:30 track becomes 127.2 BPM and runs 210 ÷ 1.06 ≈ 198 seconds (3:18), and A440 rises to 466.4 Hz, close to B♭.
Re-pitch a sample down 3 semitones
Three semitones down is a ratio of 2^(−3/12) = 0.8409, so the sample must play at about 84.09% speed. A 95 BPM loop slows to 79.9 BPM and an 8-second loop stretches to about 9.51 seconds.
33⅓ rpm record played at 45 rpm
45 ÷ 33⅓ = 1.35, a 35% speed increase. 12 × log₂(1.35) ≈ 5.20 semitones, a little more than a perfect fourth up, which is why the record sounds chipmunk-like. The 4:00 song finishes in about 2:58.
Frequently asked questions
How many percent is one semitone?+
One equal-tempered semitone is a speed ratio of 2^(1/12) ≈ 1.05946, so raising pitch one semitone needs about +5.95% speed, while lowering it one semitone needs about −5.61% (94.39% speed).
Why is +6% about one semitone on a turntable?+
Because 1.06 is very close to 1.0595, the semitone ratio. A +6% speed change raises pitch by about 1.009 semitones, so DJs treat the 6% range on a pitch fader as roughly one key step.
How do I change tempo without changing pitch?+
Use time-stretching (warp, elastic audio or a key-lock/master tempo feature). It changes duration while keeping pitch, so only the tempo and length outputs here apply, not the semitone shift.
What is a cent in music?+
A cent is one hundredth of an equal-tempered semitone, or 1/1,200 of an octave. Most listeners notice differences of around 5–10 cents between two tones played in succession.
How many semitones does slowing to half speed lower the pitch?+
Half speed is a ratio of 0.5, which is exactly −12 semitones, or one octave lower. Double speed raises pitch by exactly one octave.