How to record audio online
- Press Start recording and allow the microphone when your browser asks. The waveform moves when sound arrives.
- Optional: open Microphone and sound settings to pick a microphone, or switch off Noise suppression, Echo cancellation and Automatic gain control for music.
- Use Pause and Resume as needed, then Stop. The take appears under Your recordings with a player.
- Download it as WebM (or M4A or Ogg, whichever your browser records), WAV or MP3. MP3 quality sets the MP3 bitrate.
How the formats and sizes work
- Original: your browser's MediaRecorder compresses the sound as it records, usually WebM or Ogg with Opus in Chrome, Edge and Firefox and MP4 with AAC in Safari. This download is that file untouched, so it is the smallest.
- WAV: the take is decoded at 44,100 Hz and saved as uncompressed 16-bit audio, so size = 44 + seconds × 44,100 × 2 × channels bytes.
- MP3: encoded in your browser with the open-source lamejs encoder, which is downloaded once from a CDN the first time you press MP3. Size is about seconds × bitrate ÷ 8.
Worked example
A take of exactly 30 seconds from a mono microphone makes a WAV of 44 + 30 × 44,100 × 2 = 2,646,044 bytes. The recording card reads "Estimated size: WAV about 2.52 MB, MP3 about 468.8 KB at 128 kbps", because the default MP3 is 30 × 128,000 ÷ 8 = 480,000 bytes. A real take is a little longer or shorter, so your numbers shift slightly.
Limits and edge cases
Recordings live in memory, so closing the tab deletes them, and the page asks before you leave with unsaved takes. Only the microphone is recorded, not computer sound. WAV and MP3 conversion decodes the whole take in memory, so very long recordings can fail on phones, and the original download always works. Wear headphones when echo cancellation is off. To test your microphone first use the Mic Test, to convert an existing file use the Audio Format Converter, and for short labelled notes try the Voice Memo Recorder.
Frequently asked questions
Which format should I download: WebM, WAV or MP3?
Use the original (WebM, Ogg or M4A) for the smallest file. Use MP3 when the file has to play almost anywhere, such as on phones, in older editors or on a podcast host. Use WAV when you plan to edit the audio, because it is uncompressed, but expect a much bigger file.
Why is my recording silent or my microphone not found?
Allow the microphone when the browser asks, and check the lock icon in the address bar if you blocked it. Then choose the right device under Microphone and sound settings, make sure it is not muted in your system sound settings, and close other apps that may be using it. The Mic Test tool can confirm that sound is arriving.
Can I record computer audio or a browser tab?
No. This recorder captures the microphone only. Recording system or tab sound needs screen sharing with audio, which this page does not use.
How long can I record?
There is no fixed limit, only your device's memory, because the recording stays in the page until you download it. A one hour mono take is about 303 MB as WAV and about 55 MB as a 128 kbps MP3, and converting a very long take can fail on a phone, so download long recordings in the original format.
Sources: MDN Web Docs, MediaRecorder and MediaDevices.getUserMedia(). WAV layout: 44 byte header plus 16-bit PCM samples.