LUFS (Loudness Units relative to Full Scale) is the perceptual loudness measurement that streaming platforms, broadcasters, and podcast networks all use to set their loudness targets. A loud-but-quiet-feeling song and a quiet-but-loud-feeling song can have the same dBFS peak but very different LUFS — because LUFS accounts for how human ears actually hear loudness. This analyzer drops your track into the BS.1770-4 measurement standard and tells you exactly where it lands.
What LUFS measures and why platforms care
Spotify, YouTube, Apple Music, broadcast TV, and podcasting platforms all normalise content to a target loudness. If you master too loud, the platform turns you down — and your dynamic peaks get squashed. If you master too quiet, the platform turns you up — and you risk noise floor and compression artefacts becoming audible. The major targets: Spotify and YouTube around -14 LUFS, podcast platforms around -16, broadcast TV around -23. Hitting the target gives your audience the tone you intended. Missing it means the platform's automatic normaliser overrides your decisions.
How this analyzer works
We implement ITU-R BS.1770-4 directly in TypeScript: a K-weighting filter cascade (a high-shelf at 1681 Hz and a high-pass at 38 Hz) is applied to each channel, then 400 ms gating blocks at 75 % overlap measure mean-square energy. The integrated loudness uses absolute (-70 LUFS) and relative (-10 LU below the absolute-gated mean) gating per the spec. Loudness range follows EBU Tech 3342: 3-second short-term blocks, 95th minus 10th percentile after gating. Sample peak is reported in dBFS. Everything runs locally in your browser — no upload, no server.
When to use this tool
- Verifying a master hits the Spotify target before release (-14 LUFS)
- Levelling a podcast episode to -16 LUFS for Apple Podcasts compatibility
- Checking a broadcast deliverable against -23 LUFS R128 specs
- A/B comparing two masters' loudness to make perceptual sense of mix decisions
- Quick QA on a finished mix before sending to a mastering engineer
Frequently asked questions
- What's the difference between LUFS and dBFS?
- dBFS is a peak measurement — the loudest single sample. LUFS is a perceptual measurement that integrates over time and weights by frequency to approximate how loud a track actually sounds. Two tracks at -1 dBFS peak can be wildly different in LUFS.
- Does LRA (loudness range) matter?
- Yes. LRA is the difference between the loudest and quietest substantial sections of your track. Pop and EDM masters typically run 4-8 LU. Acoustic and orchestral material runs 12-20 LU. If your LRA is over 25 LU on a streaming track, expect platforms to compress it to fit their target.
- Can I download a normalized version?
- Yes — after analysis, four buttons let you download a copy normalized to -14, -16, -19, or -23 LUFS. The gain offset is applied with the existing browser-side DSP pipeline; no second round trip to a server.
- Is this measurement EBU R128 compliant?
- We follow BS.1770-4 (the underlying standard EBU R128 references). The implementation calibrates within ±0.5 LU of professional meters at 44.1 kHz and 48 kHz on tonal references. For broadcast delivery requiring certified measurement, use a verified meter — but for mastering and platform prep, this is accurate enough.
Privacy
Your audio file is decoded by the browser's Web Audio API and analysed entirely on your device. The DSP runs as TypeScript compiled to your browser's JIT. We have no upload endpoint — there is literally no server-side path for your audio data.