Change audio speed
Slow a lesson down or speed a podcast up, anywhere from 0.25× to 4×. The pitch stays where it was, so a voice still sounds like itself, or follows the speed like a tape if you prefer. Nothing leaves your device.
Updated October 30, 2026
Options
How it works
- Drop one or more audio files (or videos) anywhere on this page.
- Set the speed with the slider, a preset or a number, and choose whether the pitch is kept.
- Listen to the result under the file and download it.
Who reaches for this tool
Students speed a recorded lecture up to 1.5×, the default, and still follow every word. Musicians slow a solo to 0.5× or 0.75× to work it out note by note, with the pitch kept so the key does not change. Transcribers slow an interview down to type along; podcast listeners shave minutes off an episode. The speed runs from 0.25× to 4×, set by a slider, a preset or a typed number.
Pitch kept or tape
For anything you want to understand, keep the pitch: speech stays natural up to about 2×, beyond which consonants start to blur whatever the method. For learning music, 0.5× to 0.8× with the pitch kept is the sweet spot. Untick Keep the pitch when you want the effect itself: a deep slowed-down voice, a sped-up chipmunk take, or a record played at the wrong speed.
The length of the result is shown next to the speed before you start, so you know how long a 40-minute lecture becomes at 1.75×.
Batches, parts and phones
Up to 20 files can take the same speed in one list, and a video dropped here gives back its sound only, at the new speed. Drag the handles on the waveform to keep just one part, a single song on a long recording, say. Everything is decoded and encoded in your browser, so the file never leaves your device; on a phone a few minutes of audio is the practical limit, and the tool says so before it starts.
Why people use it
Free, no account
Every tool is free, with no sign-up, no e-mail address and no limit on how often you use it.
Your files stay on your device
The browser opens the file and processes it in memory, on your device. Nothing is uploaded, so nothing can be kept, leaked or looked at.
No watermark
The result is yours as it is: no watermark, no branding, no trial version.
Any device
A phone, a tablet or a computer with a current browser is enough: no app to install, no software to update.
Works offline after the first visit
The browser keeps the pages and their engines, so a tool you have opened once keeps working without a connection.
Open-source engines
The code that does the work is open-source software, named on the Licences page, running as WebAssembly in your browser.
Why it is private
Everything you type or drop here is handled by your browser, on your device. Nothing is uploaded. To verify, open your browser's developer tools, go to the Network tab, and use the tool: you will see no request carrying your data.
While a file is being processed, the counter under the result shows the page's network traffic: 0 requests and 0 B for your data.
How to check it yourself, step by step
What you can check yourself
Open your browser's developer tools on the Network tab before you drop a file: while the tool works you will see no request carrying your data, and the counter under every result shows the page's own measurement.
The site sets no cookies, so there is no cookie banner. Anonymous usage counts and error reports without file names are the only things that leave the page, as the privacy policy describes.
Every change goes through thousands of automated tests in three browser engines, including a guard that fails a test if a single byte of a file leaves the page.
Frequently asked questions
- How is the pitch kept?
- With time-stretching (WSOLA): the sound is cut into short overlapping pieces that are laid closer together or further apart, so the length changes and the notes do not. It works best on speech; on dense music at 0.5× or below, or at 2× and above, you may hear a slight echo or flutter.
- What happens when I untick 'Keep the pitch'?
- The samples are simply played faster or slower, like a tape or a record: 2× is twice as fast and an octave higher, 0.5× twice as slow and an octave lower.
- Can I change only part of the file?
- You can keep only a part: drag the handles on the waveform or type the start and end. The result is that part alone, at the new speed.
- Which format do I get?
- 'Same as the file' writes the format you dropped (an MP3 stays MP3, at its own bitrate). You can also pick MP3, WAV, AAC (M4A), Opus or FLAC. AAC, Opus and FLAC use your browser's own encoders: Firefox has no AAC encoder, so there an M4A comes back as MP3 and the result says so. A new speed always means encoding the audio once more.
- Is my file uploaded?
- No. Decoding, time-stretching and encoding run in a Web Worker in your browser, and the network meter under the result shows 0 B. The audio is held in memory while it is processed: on a computer about an hour of stereo fits, on a phone a few minutes, and the tool says so before it starts.
- Can I speed up a video with this tool?
- Only its sound: the result is an audio file. To change the speed of the picture and the sound together, use Change video speed.
- Does it work on a phone?
- Yes, in the browser, with nothing to install. Short recordings and voice notes are fine; a long album may exceed a phone's memory, and the tool tells you before it begins.
- Does the file get smaller when I speed it up?
- Usually, since it gets shorter: at 2× a recording is half as long, so at the same bitrate it is about half the size. Slowing down makes it longer and larger.
- Can I change the speed of many files at once?
- Yes, up to 20 in one list, all at the same speed and with the same pitch setting. Each result is downloaded on its own.
- What speed is good for lectures and audiobooks?
- Between 1.25× and 1.75× with the pitch kept, most speech stays clear. Above 2× it takes practice to follow, and above 3× most people miss words.
Install it as an app
Chrome, Edge and Android browsers offer to install this site from the address bar or the menu; on iPhone use Share, then Add to Home Screen. It opens like an app, keeps working offline and still processes everything on your device.