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Speed up or slow down audio

Make a song, podcast or voice recording faster or slower, from 0.25× to 4×, keeping its pitch or letting it rise and fall like a tape; the audio is processed in your browser and never uploaded.

Drop an audio fileMP3, WAV, M4A, FLAC, OGG — or a video · up to 500 MB and 10 min free
Choose audio
Runs in your browser · no uploadHow it works

How to use Change audio speed

  1. 1

    Add the recording

    Drop an MP3, WAV, M4A, FLAC, OGG or Opus file, or a video to take the sound from, up to 500 MB and 10 minutes long.

  2. 2

    Pick a speed

    Tap a preset from 0.5× to 2×, drag the slider or type an exact value between 0.25 and 4. The new length updates as you change it.

  3. 3

    Choose the pitch and listen

    Leave Keep pitch on to stay in the same key, or turn it off for a tape-style shift, then press play: the preview already runs at your speed.

  4. 4

    Save the new file

    Keep the original format or pick MP3, M4A, WAV or OGG, press Change speed and download a file named like song-1.25x.mp3.

Limits and Pro

One file at a time, up to 500 MB and 10 minutes long, at any speed from 0.25× to 4×.

Pro handles recordings of up to 4 GB and 10 hours. See Pro

About Change audio speed

Change audio speed makes a recording play faster or slower and saves the result as a new file. With Keep pitch on, only the tempo changes: a voice at 1.5× sounds like the same person talking quickly, and a song slowed to 0.75× stays in tune, so you can play along with it. This uses ffmpeg's atempo filter, which cuts the sound into short overlapping windows and lays them closer together or further apart. One pass covers 0.5× to 2×; beyond that the tool chains passes, two halvings for 0.25× for example, so each one stays where it sounds cleanest. With Keep pitch off, the samples are played back at a new rate and resampled, so pitch and speed move together like a record at the wrong speed.

The player next to the options previews the speed instantly through your browser's own playback, before anything is processed. The saved file is made by ffmpeg, so its texture can differ slightly from the preview, which relies on the browser's time-stretching.

People use it to get through lectures, audiobooks and podcasts faster, to slow a guitar solo down while learning it, to fit a voice-over or jingle to an exact length, or to undo the 4% speed-up of a film soundtrack released at 25 frames a second (0.96×).

Extreme settings have a cost: at 0.25× or 4× with the pitch kept, drums lose their punch and voices turn phasey. Title and artist tags are carried over to the new file, but embedded cover art is not.

Privacy

The recording is decoded, stretched and encoded by ffmpeg.wasm in a Web Worker inside this tab, and the preview uses your browser's built-in player, so no part of the audio is uploaded or stored anywhere. The 31 MB engine is downloaded once from jsDelivr and cached; it carries none of your sound.

Features

Pitch stays put

Change the tempo of speech or music while every voice and note keeps its key.

Hear it first

The player previews your speed instantly, before anything is processed.

Any speed

Presets, a slider and a field for exact values from 0.25× to 4×.

Tape mode

Turn Keep pitch off and the sound rises or falls with the speed.

Change audio speed: frequently asked questions

Can I speed up audio without changing the pitch?
Yes, that is the default. With Keep pitch switched on, the tool changes the tempo with ffmpeg's atempo filter, which stretches or squeezes time while each note and voice stays in its key. A podcast at 1.5× still sounds like the same host, only quicker. Switch it off when you want the chipmunk or slowed-tape effect, where the pitch follows the speed.
How much does the pitch change when Keep pitch is off?
By 12 semitones for every doubling of speed, the way a record or tape behaves. 2× raises everything an octave, 1.5× about seven semitones, 1.25× close to four, and 0.5× drops an octave. The samples are replayed at a different rate and then resampled to the original sample rate, so the length and the pitch change by exactly the same factor.
Why does the preview sound a little different from the saved file?
The preview is your browser's own player running the original at a new rate, which is instant but uses the browser's time-stretch method. The download is made by ffmpeg's atempo filter, so slow speeds in particular can sound slightly different, often a little cleaner. Speed and length are identical in both. The result screen plays exactly what you saved.
What is the slowest and fastest speed?
From 0.25×, four times as long, to 4×, a quarter of the length, set with the presets, the slider or an exact number such as 1.33. Outside 0.5× to 2× the tool chains atempo passes so each stays in its cleanest range. Expect softer drums and phasey voices at the extremes; between 0.75× and 1.5× most material still sounds natural.
Which formats can I save?
The original format when the engine can write it (MP3, M4A, WAV, FLAC, OGG, Opus or AIFF), or MP3 at 192 kbps, M4A with AAC at 192 kbps, 16-bit WAV, or OGG with Opus at 128 kbps. A video gives you its sound track only. Lossy formats are encoded again, so choose WAV or FLAC if you plan to keep editing.

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