Free tool
Tempo & Time Stretch Calculator
The percentage, playback rate and stretch ratio between two tempos — plus the length you end up with and the pitch drift if you resample.
Local arithmetic. No audio is uploaded or processed.
Tempos
Optional — to see the resulting duration.
Change
+6.667%
+8 BPM
Playback rate
1.06667×
Multiplier on speed
Duration multiplier
0.9375×
Multiplier on length
Pitch drift if resampled
+1.117 st
111.7 cents
New length
0:28.13
28.125 s
Direction
Faster
Which method to use
- Resample when the pitch change is part of the sound — drum breaks, vinyl-style pitching, tape effects.
- Time-stretch when pitch must stay put — vocals, melodic loops, anything harmonic sitting against other parts.
- Re-record or re-render when the change is large. Beyond roughly ten percent, most material starts showing artefacts that no setting fixes.
Artefact tolerance is material-dependent, so treat that ten percent as a prompt to listen rather than a limit. Related: the Pitch Shift Calculator for key changes.
Detail
How this works
The playback rate is simply target BPM / original BPM. Percentage change is that ratio minus one; the duration multiplier is its inverse, because playing faster makes audio shorter.
If you change speed by resampling, pitch moves with it by 12 × log₂(rate) semitones. That is what makes a sped-up break sound brighter and thinner. Time-stretching keeps pitch fixed instead, which is what you want for vocals and tonal material.
FAQ
Frequently asked questions
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