Is my audio uploaded to a server?

No. Everything happens locally in your browser using the Web Audio API. Your file is decoded on-device and never sent to any server.

What audio formats are supported?

Any format your browser can decode — typically MP3, WAV, OGG, FLAC, AAC, and M4A. The exact list depends on your browser and operating system.

How is stereo downmixed to mono?

Each sample in the mono output is the average of the corresponding left and right channel samples: mono[n] = (left[n] + right[n]) / 2. This is the standard mid-channel (M) downmix used in broadcast and audio production.

What format is the downloaded file?

The download is always a 16-bit PCM WAV file at the original sample rate. WAV is universally compatible with audio editors, players, and DAWs.

Will the volume change after downmixing?

The averaged downmix preserves perceived loudness well for most content. Fully correlated stereo (identical L and R) is unchanged. Fully decorrelated content (wide stereo) may sound slightly softer, which is expected behavior.

What if my file is already mono?

The tool works on mono files too — it simply passes the single channel through unchanged and produces the same audio as a WAV download.

Stereo to Mono Converter

Name: Stereo to Mono Converter
Availability: InStock
Author: Nham Vu

Load a stereo audio file, downmix it to mono (L+R averaged), and download the result as a WAV — entirely in your browser.

Load Audio File

Click or drag & drop an audio file

How Stereo-to-Mono Downmix Works

1. A stereo file stores two independent sample streams — Left (L) and Right (R).
2. The standard downmix averages them: mono = (L + R) / 2.
3. This preserves center-panned content (vocals, kick drum) at full level while the stereo width collapses to zero.
4. Hard-panned or out-of-phase content may sound softer or cancel — this is expected mono-compatibility behavior.

Load an audio file to convert it

Summary

Load a stereo audio file, downmix it to mono (L+R averaged), and download the result as a WAV — entirely in your browser.

How it works

Click "Choose File" and select any stereo audio file (MP3, WAV, OGG, AAC, FLAC, or other browser-supported format).
The tool decodes the file in the browser and reads both the left and right channel sample arrays.
Each sample pair is averaged — (L + R) / 2 — to produce a single mono channel at the same sample rate.
Click Preview to play back the downmixed mono audio directly in the page.
Click Download WAV to save the mono result as a 16-bit PCM WAV file.

Use cases

Prepare a voice-over recording for broadcast systems that require mono audio.
Reduce file size by halving channel count before transcoding or uploading.
Check mono compatibility before publishing a podcast or radio ad.
Convert a stereo interview recording to mono for a transcription service.
Downmix a music stem to mono for use in a mono PA system.
Remove stereo imaging artefacts from a lopsided recording.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu