Stereo Mono Converter

About Stereo Mono Converter

This free online tool allows you to convert audio between stereo and mono formats. Stereo audio has two separate channels (left and right), while mono audio has a single channel. Converting between these formats is useful for various audio production and compatibility needs.

What is the difference between Stereo and Mono?

Stereo audio has 2 channels (left and right) that can play different sounds, creating a spatial effect. Mono audio has 1 channel where the same sound plays through all speakers. Stereo provides a richer listening experience, while mono ensures consistency across all playback devices.

When should I convert Stereo to Mono?

Convert to mono when: recording podcasts or voice content (stereo isn't needed), reducing file size (mono is half the size), ensuring compatibility with mono playback systems, or when the stereo effect isn't important for your content.

When should I convert Mono to Stereo?

Convert to stereo when: a platform requires stereo format, mixing mono recordings with stereo tracks, preparing audio for video editing software that expects stereo, or when you need compatibility with stereo-only systems.

Does converting Mono to Stereo create true stereo sound?

No. Converting mono to stereo simply duplicates the single channel to both left and right. It won't create the spatial separation of true stereo recordings. The result sounds the same but is formatted as stereo for compatibility purposes.

Will the conversion affect audio quality?

The channel conversion itself doesn't reduce quality. However, the audio will be re-encoded. Select 'High Quality' (320kbps) to maintain the best possible quality. Converting stereo to mono may reduce the perceived richness if the original had significant stereo separation.

What audio formats are supported?

FFmpeg.wasm decodes a wide range of inputs: MP3, WAV, FLAC, Opus, OGG, AAC, M4A, WebM and most video containers (MP4, MKV, MOV). You can keep the same output format or render to MP3, WAV, OGG, or AAC. Sample rate and bit depth are preserved unless the output codec dictates otherwise.

What happens to the level and phase when I sum stereo to mono?

Summing L and R can cause phase cancellation: any content that is out of phase between channels (correlation below 0) partially or fully disappears in mono. It can also clip, because two correlated signals add up to roughly +6 dB. This tool measures the inter-channel correlation and the predicted mono peak before you render, so you can spot cancellation or clipping in advance and pick a safer downmix law.

Should I use the 0.5 average or the -3 dB (0.707) downmix?

The Average law (0.5·L + 0.5·R) is FFmpeg's default and keeps fully correlated mono content at the same level. The -3 dB law (0.707·L + 0.707·R) follows ITU-R BS.775 and keeps the loudness of uncorrelated stereo (e.g. a wide mix) closer to the original, at the cost of up to +3 dB on correlated material, which can clip. Choose Average for safe headroom, -3 dB to match broadcast/DAW downmixers, or Left/Right/Side to isolate a single component.

Why is converted mono-to-stereo not true stereo?

Converting mono to stereo produces dual-mono: the same signal in both channels. It is fully correlated (correlation +1) and sounds identical to the mono source, just stored as two channels for compatibility. It does not add any stereo width or spatial separation; only a true stereo recording or a widening/decorrelation process can do that.

Is my audio file uploaded to a server?

No! All processing happens directly in your browser using FFmpeg.wasm technology. Your audio files never leave your computer, ensuring complete privacy.