How to Use the Time-Stretch Calculator
- Enter the Original BPM.
- Enter the Target BPM.
- Add the original audio length in seconds.
- Select Calculate stretched length.
- View the new duration.
The calculator accepts decimal tempo values between 20 and 400 BPM. It works as a lightweight Time stretch calculator app in your browser, with no installation, account, or audio upload required.
Tool Features
- Calculates audio duration at a different tempo
- Supports decimal BPM values
- Works with loops, samples, tracks, and DJ edits
- Performs calculations locally in the browser
- Requires no audio upload
- Works as a practical Time calculator, Tempo calculator, and BPM percentage calculator
- Calculates timing without editing the audio file
Time-Stretch Formulas
New Audio Duration
Playback-Speed Ratio
Playback-Speed Percentage
BPM Percentage Change
A duration below the original value means the audio must play faster. A duration above the original value means it must play slower.
A playback speed of 125%, for example, means the audio plays 25% faster than its original speed.
Time-Stretch Calculation Example
Suppose an audio clip has these values:
- Original BPM: 120
- Target BPM: 150
- Original length: 60 seconds
Calculation:
The clip becomes 48 seconds long.
Its required playback speed is:
This means the audio must play 25% faster.
BPM and Duration Table
| Original BPM | Target BPM | Original Length | New Length | Speed |
|---|---|---|---|---|
| 120 | 150 | 60 seconds | 48 seconds | 125% |
| 120 | 90 | 60 seconds | 80 seconds | 75% |
| 100 | 125 | 30 seconds | 24 seconds | 125% |
| 128 | 120 | 16 seconds | 17.067 seconds | 93.75% |
| 140 | 70 | 8 seconds | 16 seconds | 50% |
Time Stretching, Pitch and Varispeed
Time stretching changes audio duration while pitch-preserving software attempts to maintain the original musical key. This calculator only predicts the required timing change; it does not process or modify audio.
Traditional varispeed changes speed, duration, and pitch together. A dedicated Varispeed calculator may also estimate the resulting pitch shift.
For musical transposition, use a separate Semitone calculator pitch tool. This calculator does not calculate semitone or key changes.
Accuracy and Limitations
The duration result is mathematically accurate for the entered BPM and length values. Actual sound quality depends on the DAW, stretching algorithm, source material, and size of the tempo change.
Large tempo adjustments may cause:
- Softened drum transients
- Metallic or phase-like sounds
- Modulation artifacts
- Unnatural vocal results
Test a short section before processing or rendering the complete file.
Frequently Asked Questions
What does a Time-Stretch Calculator do?
A Time-Stretch Calculator finds the new duration of audio after its tempo changes. It uses the original BPM, target BPM, and original length to calculate how long the resulting clip should be.
How do I calculate the time-stretch percentage?
Divide the target BPM by the original BPM and multiply by 100:
Changing 120 BPM to 150 BPM requires a playback speed of 125%.
Does time stretching change the pitch?
Pitch-preserving time-stretch software can change duration while attempting to maintain the original pitch. Traditional varispeed changes both speed and pitch. This calculator only provides timing values and does not process audio.
Can I enter decimal BPM values?
Yes. The Time stretch calculator BPM inputs support decimal values, such as 120.5 or 128.25 BPM, for more precise duration calculations.
Can this calculator stretch or download my audio?
No. The tool does not upload, edit, preview, render, or download audio files. It calculates the required duration and speed so you can apply those values in a DAW or audio editor.