Audio Tempo Changer Online

Tempo is the speed of music, measured in BPM (beats per minute). Changing tempo means making audio play faster or slower while keeping the pitch — the notes — exactly the same. This is called time-stretching.

Our audio tempo changer online uses ffmpeg's battle-tested atempo filter to change audio speed without any pitch artifacts. The result sounds natural at any speed from 0.25× to 3.0×.

Why DJs and Producers Use Tempo Changing

• Practice beatmatching at a slower speed before performing live
• Speed up samples to fit a higher-BPM project without re-recording
• Slow down complex solos or fills to learn them note by note
• Create dramatic slow-motion or fast-forward effects in productions
• Reduce podcast duration by speeding up recordings slightly

ffmpeg's atempo filter uses a phase vocoder algorithm to time-stretch audio. It analyzes overlapping short-time frames of the audio, adjusts the timing between frames, and reconstructs the signal at the new speed — all without changing the frequency content (pitch).

The filter natively accepts values between 0.5 and 2.0. For speeds outside this range (like 0.25× or 3.0×), our tool automatically chains multiple atempo filters:

All processing runs in your browser via ffmpeg.wasm — the full ffmpeg library compiled to WebAssembly. Your audio file never leaves your device.

These two concepts are often confused but are completely independent:

Use our Pitch Changer tool if you want to transpose the key of a track without changing its speed.