NEW · FFmpeg.wasm · 100% Browser-Based

Audio Normalizer

Normalize audio to broadcast-standard loudness — EBU R128 two-pass, ITU BS.1770. FFmpeg.wasm runs locally. No upload, no signup, no watermark.

🎵
Drop an audio file
MP3 · WAV · AAC · OGG · FLAC · M4A
Files stay on your device · Never uploaded

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Why Do This in Your Browser?

Loudness normalization is one of the genuinely useful audio tasks that almost every distribution platform now mandates. Spotify normalizes to -14 LUFS; Apple Music to -16 LUFS; YouTube to -14 LUFS; broadcast (EBU R128) to -23 LUFS. Submitting content above those targets gets it automatically reduced, often with subtle artifacts; submitting below leaves listeners reaching for the volume knob.

FFmpeg's `loudnorm` filter implements EBU R128 two-pass normalization — the broadcast standard. Pass one measures the input's integrated loudness, peak, and dynamic range; pass two applies the corrections to land precisely at the target LUFS. The browser version runs both passes locally, with the same math as desktop FFmpeg.

How It Works

Drop a file and pick a target. Built-in presets cover the common cases: Spotify (-14 LUFS), Apple Music (-16 LUFS), YouTube (-14 LUFS), EBU R128 Broadcast (-23 LUFS), AES Streaming (-18 LUFS), Voice/Podcast (-16 LUFS, more headroom). Custom mode exposes target LUFS, true peak (default -1 dBTP), and loudness range (default 11 LU).

Pass one runs an analysis. The tool displays measured integrated loudness, true peak, and loudness range — useful diagnostics on the source. Pass two applies the correction. Output sample format matches the input (you can override to PCM 16-bit WAV for archival, or compressed format with separate compression settings).

Tip: Normalize after final mixing — normalization on a partially-mixed file doesn't help if you're going to make more changes later. Combine with the Audio Compressor tool for final delivery — normalize first, compress second. For brickwall safety on the peaks the loudness boost can push past 0dB, follow up with the Audio Peak Limiter at -1dB ceiling.

Common Use Cases

Podcast Distribution
Apple Podcasts, Spotify, and YouTube each have a loudness target. Normalize before upload to avoid platform-side reduction.
Music Mastering Final Pass
Streaming services normalize on playback; normalizing your master to match avoids surprises on listener volume.
Audiobook Production
ACX (Audible) requires -23 to -18 LUFS — normalization is mandatory for narrator-submitted audiobooks.
Broadcast Compliance
EBU R128 (-23 LUFS) is the European broadcast standard; US ATSC A/85 (-24 LUFS) similar. Compliance is required for broadcast delivery.
Voice-Over for Video
Match VO levels across multiple recordings before importing into a video editor.
Batch-Match Recordings
Apply the same target to multiple files — useful for archive cleanups where source levels vary.

How We Compare

Honest read on free, paid, and self-hosted options for this kind of job:

UDT Audio Normalizer (this tool): Free, browser-based, FFmpeg.wasm loudnorm two-pass (EBU R128). All major presets + custom target. Shows measured loudness, peak, range. No upload, no watermark, no signup.
iZotope RX / Ozone: Industry-standard mastering suites with sophisticated normalization. $199–$499; desktop.
Auphonic: Cloud-based; specialized for podcasts; free tier 2hr/month; paid plans from $11/mo.
Adobe Audition: Excellent loudness tools, including ITU R128; Creative Cloud $20+/mo.
Audacity (desktop): Free, has ITU-R BS.1770 loudness normalization built in. Excellent; this browser tool is the focused alternative.
FFmpeg CLI: Free, command-line; same engine as this tool. This is FFmpeg with a UI.

Frequently Asked Questions

Is this audio normalizer really free?+
Yes — completely free, no watermark, no time limits, no signup. The site is supported by ads elsewhere; the tool is unrestricted.
What is LUFS and why does it matter?+
LUFS (Loudness Units relative to Full Scale) is the modern standard for measuring perceived loudness — replacing the old peak-based dB measurement. Streaming and broadcast platforms target specific LUFS levels so listeners don't have to adjust volume between content. Common targets: -14 LUFS (Spotify, YouTube), -16 LUFS (Apple Music), -23 LUFS (EBU R128 broadcast).
Are my audio files uploaded anywhere?+
No. FFmpeg.wasm runs entirely in your browser. The 32MB engine downloads once and caches; after that, the tool works fully offline.
What's the difference between peak normalization and loudness normalization?+
Peak normalization scales audio so the loudest sample hits a target (e.g., -1 dBTP). Loudness normalization (this tool) measures perceived loudness across the entire file and adjusts so the average matches the target — much closer to how humans actually perceive volume. Streaming platforms all use loudness normalization, not peak.
Why two-pass?+
Pass one analyzes the entire file to measure integrated loudness, peak, and loudness range. Pass two uses those measurements to apply correctly-scaled corrections. Single-pass normalization (sometimes called 'dynamic') makes corrections in real-time and can over- or under-shoot the target.
What target should I pick?+
Spotify/YouTube: -14 LUFS. Apple Music: -16 LUFS. Podcast (any platform): -16 LUFS is a safe pick. ACX audiobooks: -18 LUFS. EBU R128 broadcast: -23 LUFS. AES streaming: -18 LUFS. When in doubt, -16 LUFS works for most distribution scenarios.
What's true peak and why does it matter?+
True peak measures the loudest inter-sample peak after digital-to-analog conversion. Even if your digital samples don't clip, the analog reconstruction can. Setting true peak to -1 dBTP (1 dB below digital max) gives a safety margin against playback clipping. Most streaming platforms recommend -1 dBTP.
What's the underlying engine and license?+
FFmpeg.wasm v0.12.x with @ffmpeg/core v0.12.6 (loudnorm filter implementing EBU R128 / ITU BS.1770 built in). FFmpeg itself is LGPL-licensed; the wasm wrapper is MIT.

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