That folder of music you've collected for years — some tracks whisper, some shout. LevelAudio measures how loud every MP3, WAV and FLAC actually feels and brings them all to one volume. No re-encoding for MP3s, no squashed dynamics, no clipping. Free, in your browser.
Loudness isn't peaks and volume knobs — it's how loud a track feels. LevelAudio measures it the way broadcasters and streaming platforms do (LUFS), shows you every track's numbers, and only then touches anything.
Choose a folder — subfolders, mixed formats, thousand-track collections welcome. In Chrome and Edge, results are written back next to your originals; everywhere else you get a ZIP.
Every track gets a K-weighted loudness reading and a true-peak check — the same measurements Spotify and YouTube use to judge volume. You review everything before a single byte is written.
Pure gain, nothing else: quiet tracks come up, loud ones come down, the mix stays exactly as mixed. A true-peak ceiling keeps everything clip-free — and you can A/B any track before committing.
LevelAudio never processes more than it has to, and it always shows which method each file got.
MP3 frames carry a gain field in their headers. LevelAudio rewrites just that field (the mp3gain technique) in 1.5 dB steps — the audio data, tags and cover art stay byte-for-byte identical, and the change can be undone.
Measurement and WAV gain run in hand-written BS.1770-4 code — sample-exact math at the file's own bit depth, off the UI thread. Your files never change quality class.
Odd encodings, FLAC re-encodes, hour-long recordings: a bundled FFmpeg (WebAssembly) steps in with two-pass EBU R128 loudnorm. It loads once and runs on your device, like everything else.
Cloud converters make you upload files one by one, wait in a queue, and hand your collection to someone else's server. LevelAudio skips all of it — your own machine does the work:
normalized/ folder next to them.Network tab — it stays quiet.)No — and this is the part loudness tools usually get wrong. LevelAudio applies pure gain: the whole track moves up or down together, like turning the volume knob once and leaving it. No compression, no limiting, no pumping. The quiet intro and the loud chorus keep exactly the distance the mix gave them. If a track can't reach the target without its peaks hitting the ceiling, LevelAudio applies less gain and tells you, rather than squashing it.
Yes. Your machine does the work, so each user costs us almost nothing — that's why we can afford to be generous. If LevelAudio saved your library an afternoon, there's a pay-what-you-want tip jar.
Your browser opens them, measures and adjusts them in memory, and writes results back to your disk (or hands you a ZIP). Nothing is uploaded or stored anywhere else — there's no server side to this tool at all.
MP3 volume can be changed by rewriting a gain field inside each frame instead of decoding and re-encoding the audio. Quality is untouched, tags and album art are preserved byte-for-byte, and the adjustment is exactly reversible. The trade-off: it works in 1.5 dB steps, so tracks land within ±0.75 dB of the target — inaudible in practice. Prefer sample-exact? Switch MP3 handling to "exact re-encode" in the app.
−14 LUFS (the default) matches Spotify, YouTube and most streaming platforms and is a good all-round choice for personal libraries. −16 LUFS is the common recommendation for podcasts. −23 LUFS is the EBU R128 broadcast standard. All targets are enforced with a true-peak ceiling so nothing clips.
FLAC is compressed, so a gain change means decoding and re-encoding. The re-encode is done at the file's own bit depth and sample rate with FLAC's lossless compression — you end up with a normal FLAC file of the same quality class. It's still a more invasive operation than the MP3 patch, which is why the app tells you which method was used, per file.
A modern browser. Chrome and Edge can write results straight back into the folder you picked (new "normalized" subfolder, or in place if you ask). Firefox and Safari read folders fine and hand results back as a ZIP download.