Tempo Percentage Change Calculator
Change a tempo by a percentage to get the new BPM, the resulting track duration and the pitch shift in semitones if tempo and pitch are linked.
How it works
New BPM = old BPM × (1 + %/100) · New length = old length ÷ (1 + %/100) · Pitch shift (semitones) = 12 × log₂(1 + %/100) when pitch is linked to speed
Changing tempo by a percentage simply scales the BPM: +10% multiplies it by 1.10. The running time moves the opposite way — a faster tempo means a shorter track — so the new length is the old length divided by the same ratio. Modern software can stretch time without touching pitch, but old-school varispeed (like speeding up a tape or record) links the two: the pitch rises by 12 × log₂(ratio) semitones, which is why a sped-up track also sounds higher.
Worked example
Take a 120 BPM track and speed it up 10%. The new tempo is 120 × 1.10 = 132 BPM. A 4:00 (240 s) track becomes 240 ÷ 1.10 ≈ 218 s (3:38). With linked varispeed the pitch rises 12 × log₂(1.10) ≈ 1.65 semitones.
Frequently asked questions
Does changing tempo change the pitch?
It depends on the method. Time-stretching algorithms in a DAW keep the pitch the same while changing tempo. Varispeed — physically playing faster, as with a tape or turntable — raises both together, by 12 × log₂(ratio) semitones.
How much percentage is one semitone?
One semitone up is a ratio of 2^(1/12) ≈ 1.0595, i.e. about +5.95%. Down one semitone is about −5.61%. So a ±6% pitch adjustment on a DJ deck is roughly a semitone.
Why does a faster tempo make the track shorter?
The same number of beats plays in less time. If you multiply the tempo by 1.10 you cover the arrangement 10% faster, so the duration divides by 1.10 — about 9.1% shorter.
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This calculator is for educational purposes. Double-check important results before acting on them.