Music & audio
Tempo speed-change calculator
Compare tempo, duration and pitch when playback speed changes.
A clear answer. Here’s how.
Playback speed ratio = target BPM / original BPM. New duration = original duration / ratio. Without pitch-preserving time stretching, pitch shifts by 12log₂(ratio) semitones. Shows both the time-stretch percentage and pitch consequence; no recording is modified.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Original quarter-note BPM
- 100
- Target quarter-note BPM
- 120
- Original duration (seconds)
- 180
Example result
- Playback speed ratio
- 1.2
- New duration (seconds)
- 150
- Duration as percentage of original
- 83.3333333333%
- Pitch change without pitch preservation
- 3.15641287001 semitones