Select an audio file and encode locally in your browser using LAME 4.0 with VBR, cVBR, cVBRb, ABR or CBR. Advanced users can control constrained VBR, bitrate boost, ID3 tags, cover art, output names and the technical conversion log.
Common browser-readable audio and video files can be converted locally. Very large files may be limited by browser memory.
The quick menu covers common choices. In VBR mode, the V0–V9 quality value is the main control and a bitrate target is not required. cVBR uses the selected VBR quality with a strict minimum bitrate; enabling bitrate boost gives cVBRb. ABR and CBR use the bitrate field. For modern LAME VBR, algorithm-quality values 0–4 use the highest internal VBR analysis path, so the VBR quality value is usually the setting that matters.
Filter values: use 0 for LAME's automatic/default behaviour, -1 to disable that filter, or enter a cutoff frequency in Hz. A low-pass attenuates frequencies above the cutoff; a high-pass attenuates frequencies below it. Keep manual cutoffs below half the selected output sample rate (for example, below 22,050 Hz at 44.1 kHz).
ID3 tags are written locally in the browser after encoding. Smaller cover images are recommended to avoid unnecessarily large MP3 files.
Ready.
This tool converts supported audio and video files to MP3 directly in your browser. It uses a WebAssembly encoder based on LAME 4.0 and exposes CBR, VBR, cVBR/cVBRb and ABR MP3 output. Your selected file is processed locally on your device and is not uploaded to lamemp3.co.uk.
The web encoder provides true LAME -V VBR control plus cVBR and cVBRb directly in the browser. Use the downloadable Windows builds when you need command-line use, batch encoding, scripting, or other separately maintained branch features.
High-pass and low-pass filters can be used together to concentrate the encoded frequency range on speech. This can reduce unwanted rumble or hiss and, at lower bitrates, avoid spending MP3 data on frequencies that contribute little to the programme.
For natural podcast or audiobook speech: a high-pass around 80–100 Hz is a useful starting point for reducing low-frequency rumble and plosives while retaining the body of most voices. Leave the low-pass on 0 (Auto) unless you have a reason to narrow the upper range.
For speech-focused or bandwidth-conscious encoding: a low-pass around 12–16 kHz can reduce high-frequency content while retaining substantially more naturalness than telephone-style speech. For a deliberately compact, voice-centred sound, an upper limit around 7–8 kHz is comparable to the bandwidth used by wideband speech systems, but it will sound less open than a normal podcast master.
For noisy archival narration or storytelling: try a high-pass around 80–125 Hz and, only if high-frequency hiss is objectionable, gradually lower the low-pass while previewing the result. Avoid using a narrow speech band unless intelligibility and file efficiency matter more than natural timbre.
These are starting points rather than fixed rules. Filter cutoffs are transition points, not brick walls, and the best values depend on the voice, microphone, background noise, output bitrate and intended sound. For music or mixed music-and-speech material, LAME's automatic filtering is normally the safer default.
Use the Online MP3 Encoder for the simpler audio-focused workflow, including ID3 tags, cover art and output naming. Use the Video & Audio to MP3 Converter when you want to extract audio from video, handle broader media inputs or process long files with memory-managed FFmpeg decoding. Use the Windows command-line builds for batch processing, scripting or exact command-line control.
The conversion runs locally in your browser. Your selected media file is not uploaded to this website.
The online encoder uses a standalone LAME 4.0 WebAssembly bridge. It exposes VBR, cVBR, cVBRb, ABR and CBR modes, plus optional algorithm-quality and filter controls. cVBR uses a strict minimum bitrate; cVBRb is the same constrained VBR path with bitrate boost enabled.
Use Advanced Options for VBR, cVBR/cVBRb, ABR and CBR settings, ID3 tags, cover art, filename choices and the technical conversion log. For batch work and command-line automation, use the Windows builds.
Encoder note: this page uses a standalone LAME 4.0 WebAssembly bridge with VBR, cVBR, cVBRb, ABR and CBR support, including Xing/LAME VBR headers for correct duration reporting in typical players. VBR uses V0–V9 as its main quality control. cVBR adds a strictly enforced minimum bitrate, while cVBRb uses the same constrained VBR path with Light, Medium or Aggressive bitrate boost. Read the cVBR comparison.
The online encoder uses the same LAME encoder core compiled to WebAssembly. For a small DeltaWave-based check against the Windows command-line builds, see the comparison notes.