Change MP3 Speed Online
Free, No Upload, 0.25× to 4×

▍What is the sound-goods Speed Changer?

The sound-goods Speed Changer is a free browser-based tool that lets you change the playback speed of any audio file — from quarter speed (0.25×) to four times fast (4×) — without uploading anything. The processing runs entirely in your browser using the Web Audio API, which lets your device's audio engine resample the audio at any playback rate and re-encode it as a 192kbps MP3 via lamejs.

Unlike most tools that only offer fixed presets (0.5×, 1.5×, 2×), sound-goods gives you a continuous slider for exact control, independent pitch shifting in semitones, and a live duration preview so you know the output length before you export.

▍How to change MP3 speed — step by step

▍Features

▍Speed reference guide

Not sure which speed to use? Here are the most common speeds and what they're used for:

▍sound-goods vs. other speed changers

▍Speed change vs. time-stretching — what's the difference?

This is the most important technical concept to understand about audio speed changing, and most tools explain it poorly.

Speed change (what sound-goods does) works exactly like a vinyl record played at the wrong RPM. When you double the speed, the audio plays in half the time — and the pitch rises by exactly one octave. When you halve the speed, it plays twice as long — and the pitch drops an octave. The relationship between speed and pitch is mathematically fixed. This is what produces the "chipmunk" effect at fast speeds and the "deep voice" effect at slow speeds.

Time-stretching (used by professional DAWs and tools like LALAL.AI or Audacity's Change Tempo) separates pitch from tempo using algorithms like WSOLA, phase vocoder, or elastic audio. This allows you to slow a recording to 0.5× without any change in pitch — the voice sounds the same, just slower. Time-stretching at high quality requires significant computation and often produces artifacts (metallic "smearing") at extreme settings.

▍Common use cases

Nightcore and lofi edits

Nightcore is the genre defined by speeding up a song to 1.25×–1.5× — which raises the pitch and creates a characteristic energetic, anime-adjacent sound. Set the slider to 1.3× or 1.4×, preview it, and export. No pitch compensation needed — the pitch shift is the point.

Slowed + reverb

The reverse of nightcore. Set the slider to 0.75×–0.85× for the classic slowed aesthetic. The pitch drops naturally, giving vocals a melancholic, dreamy quality. Pair with a reverb plugin in your DAW after export for the full effect.

Podcast and audiobook speed-up

Set to 1.25× or 1.5× to consume long-form spoken content faster. At 1.25×, the pitch shift is only about 3 semitones — barely perceptible for voice content. Use 1.5× for a more aggressive speed-up with the same minor pitch rise.

Language learning

Slow down a native speaker recording to 0.75× to hear individual words and phonemes more clearly. The 5-semitone pitch drop is noticeable but doesn't interfere with comprehension. As your listening skill improves, gradually increase back toward 1×.

Music transcription and learning

Slow a fast musical passage to 0.5× to transcribe notes or learn a difficult run. For guitar, piano, or horn passages, being able to slow to half speed and still hear the individual notes clearly is essential for learning by ear.

Creating pitch-shifted versions

Use the speed slider at 1× and adjust only the pitch control to transpose a song to a different key. Moving +2 semitones raises by a whole step; −5 semitones drops a minor third. Useful for practicing a song in a key that suits your vocal range.

▍Frequently asked questions

Need to trim your audio before or after changing speed? Use our MP3 Cutter. Want to merge the result with another track? Try the MP3 Merger.