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Audio Time Stretch

Change audio playback speed without affecting pitch. Perfect for learning music, creating slow-motion effects, or speeding up audiobooks while maintaining natural sound.

Free to use, no watermarks, runs in your browser—nothing uploads to our servers

Source file

Files are processed locally in your browser using WebAssembly.

Saved FFmpeg presets (stored locally)

Saved presets

Preset name

Speed Multiplier

Playback speed multiplier (0.25x = 4× slower, 2.0x = 2× faster, 1.0x = original speed)

Quick Presets

Use Cases

• 0.5x-0.75x: Learning music, transcription, practice
• 1.1x-1.25x: Faster audiobook listening
• 1.5x-2.0x: Quick content review, efficient consumption
• 2.0x+: Creative effects, time-lapse audio

Jump to helper sections

What is time stretching?

Time stretching changes the speed (tempo) of audio without changing its pitch. A song at 1.5x plays faster but stays in the same key. At 0.75x it plays slower but maintains original pitch.

What speeds can I use?

You can adjust from 0.25x (4 times slower) to 4.0x (4 times faster). Common uses: 0.75x-0.9x for practice, 1.1x-1.25x for efficiency, 1.5x-2.0x for quick review. Extreme speeds (below 0.5x or above 2x) may introduce artifacts.

Will time stretching affect audio quality?

Modern time-stretching algorithms preserve quality well at moderate speeds (0.5x-2.0x). Extreme stretching can cause artifacts like phasing or robotic tones. Music with clear rhythm stretches better than complex orchestral pieces.

Can I slow down music to learn it?

Absolutely! Slowing to 0.75x or 0.5x is perfect for learning songs, transcribing music, or practicing difficult passages. The pitch stays the same so you can play along with your instrument.

Report a bug

If this tool misbehaves, share a quick summary so we can investigate. We include the tool URL automatically—no need to copy and paste.