To change audio speed in Audacity, open the file, choose Effect > Change Speed, enter a playback rate such as 200% (twice as fast) or 50% (half speed), preview the change, then click OK to render the new speed into the track. Audacity's Change Speed effect rescales the entire selection by a single uniform factor, so a 100% setting is the unchanged original, 200% plays the file twice as fast in roughly half the time, and 50% plays it half as fast in roughly double the time. The change happens locally on your machine, your source file is never re-rendered in the cloud, and the result is written back into the same track at the project sample rate, ready for further editing or for export to WAV, MP3, or any other format Audacity supports through its optional FFmpeg library. Because both playback rate and pitch shift together, this is the right tool for a quick reference copy of a long lecture, a sped-up podcast draft, or a slowed-down clip to feed into transcription. A track-level change applies to the full waveform, while a region-level change applies only to the highlighted portion, leaving the rest of the project at its original speed.
Most readers land on this question because they need a faster reference copy of a long recording, a slower clip for catching every word, or a short jingle stretched to fit a video edit. Audacity can deliver all three, but installing the desktop app, importing a file, choosing an effect, and exporting the result adds up to several clicks and a short loading pause. The same task, speeding up or slowing down a browser-decodable audio file and downloading a clean WAV, can be completed in a single page without installing anything. Below is the full Audacity walkthrough first, then a quick browser alternative that produces a WAV ready for handoff to another local editor.
What "Changing Audio Speed" Actually Means
Speeding up or slowing down audio reshapes the timeline: a 60-second source played at 2× finishes in about 30 seconds, and the same source played at 0.5× stretches to about 120 seconds. The math is the same relation Audacity applies under the hood, where new duration equals the original duration divided by the playback-rate factor. Speeding up a 60-second source to 2× gives 60 ÷ 2 = 30 seconds, while slowing the same source to 0.5× gives 60 ÷ 0.5 = 120 seconds.
This shortcut comes with a side effect that matters when working with spoken word or music: pitch moves along with speed. Doubling playback rate lifts every voiced sound up by roughly an octave, and halving playback rate drops every voiced sound down by an octave. For a podcast reference copy or a sped-up tutorial review the pitch shift usually does not matter, but for a song you want to time-stretch without chipmunking the vocals, Audacity offers a separate Effect > Change Tempo that calls its time-stretching library and retunes the audio as it stretches. The Change Speed effect does not invoke the time-stretch library, so it is faster but not pitch-preserving, which is exactly why it reads plainly as "Change Speed" rather than "Change Tempo."
How to Change Audio Speed in Audacity
- Open Audacity and import your audio file with File > Open > Open File, or drag the file directly onto an empty project window. Audacity supports WAV, AIFF, FLAC, OGG, and MP3 when the optional FFmpeg library is installed.
- Select the track or the region you want to adjust. Click the track's name panel to select the entire track, or click and drag across the waveform to highlight only a specific region. If you select a portion, only that portion is rescaled and the rest of the project stays at the original rate.
- Open Effect > Change Speed from the top menu. The dialog shows a Percent Playback Rate field and a slider that defaults to 100%. Type a new value or drag the slider, where 200% doubles the speed and halves the duration, and 50% halves the speed and roughly doubles the duration.
- Click Preview to listen before committing. If the result feels too extreme or too subtle, adjust the percentage and preview again until the rate matches your goal.
- Click OK to render the speed change into the selected audio, or Apply to keep the dialog open for further tweaks. The new waveform appears at a different length on the timeline.
- Undo with Edit > Undo at any point, or simply close the project without saving if you want to discard the change entirely.
- Export the result with File > Export. Choose WAV for an uncompressed local handoff, or pick another supported format. The export dialog writes the resampled audio to your chosen file.
The whole flow stays local: Audacity never sends audio to a remote server, and Apply can be repeated for incremental speed adjustments before exporting the final file.
A Faster Browser Alternative for Quick Speed Changes
For users who do not want to install Audacity, configure FFmpeg, or open a full desktop editor, an Audio Speed Changer in the browser completes the same speed-and-export task in just a few clicks. The page accepts a browser-decodable audio file up to 25 MB, renders it at the chosen rate entirely through a local Web Audio API OfflineAudioContext, and exports the result as an uncompressed PCM16 WAV file that follows the standard RIFF/WAVE structure.
Because nothing leaves the machine, the workflow fits private voice memos, lecture audio, or any clip you would rather not hand to a cloud service. The page also reports the new duration and the file size so you can confirm what you are about to download before committing. The selected file is decoded locally, routed through an offline audio renderer at the chosen rate, and exported as a fresh PCM16 WAV file that any other local editor or audio player can open.
How to Use Audio Speed Changer
- Choose an audio file up to 25 MB using the file picker. The file is decoded locally in your browser, and no upload happens at any point in the process.
- Wait for the audio to finish decoding, then pick a speed from the 0.5× to 2× selector. Faster or slower playback changes pitch together with duration, mirroring the same physical behavior as Audacity's Change Speed.
- Select Change speed and export WAV to render the new file. If decoding or rendering fails, no output file is written.
- Preview the result inside the page, including the reported duration and file size, to confirm the change before saving.
- Download the PCM16 WAV file to your device. The output is bounded before rendering and is not emitted when decoding or rendering fails.
Choosing a Speed: Use Cases at a Glance
| Playback rate | What it does | Best for |
|---|---|---|
| 0.5× | Half speed, longer duration | Transcribing dense speech, learning a tricky musical passage |
| 0.75× | Slightly slower, easier to follow | Podcast replay, note-taking while listening |
| 1× | Original rate, no change | Baseline export for handoff to another editor |
| 1.25× | Somewhat faster, mild pitch lift | Revisiting familiar lectures more efficiently |
| 1.5× | Noticeably faster, audible pitch shift | Speed-listening material you already understand |
| 2× | Half the length, pitch shifted up | Quick scan of a long recording or podcast overview |
The exact durations and file sizes for your source material come from the preview panel in Audio Speed Changer, so the precise seconds-per-minute figures stay tied to the rendered result rather than a generic guess. The table above describes each setting qualitatively in line with how Audacity's Change Speed dialog and the browser tool both behave.
Privacy, Limits, and What the WAV Keeps
Audio Speed Changer does not upload the source file. Decoding, offline rendering, previewing, and WAV creation all run inside the browser tab. The downloaded file is uncompressed PCM16 WAV, so its file size on disk is typically larger than the original compressed audio even when its duration is shorter, since uncompressed WAV simply uses more storage per second than MP3 or AAC. The download deliberately uses uncompressed PCM16 WAV for a clear, broadly readable local result.
Several limits are enforced up front for predictable browser memory use. Input files are capped at 25 MB, 15 minutes, eight channels, 192 kHz, and 30 million rendered samples. The output does not preserve the source codec, bitrate, ID3 tags, artwork, chapters, or other embedded metadata, and it does not create an MP3. Browser codec support varies, so a file that your current browser cannot decode will surface an error and no output file is created. For users who want a quick reference copy, a slower practice version, or a clean WAV handoff to another local editor, the combination of Audacity's full DAW controls and the lightweight browser tool covers the same task at two different scales of effort.