LUFS Loudness Checker: Measure Loudness of Audio Files

Choose an audio file

Drag & drop your audio here

MP3 · WAV · M4A · OGG · FLAC — decoded locally, never uploaded

How it works

The same EBU R128 standard the streaming platforms use — implemented in pure JavaScript.

1

Decode locally

Your file is decoded in-browser with the Web Audio API — MP3, WAV, M4A, OGG, FLAC. Nothing is sent anywhere.

2

K-weight & measure

The signal is K-weighted (BS.1770), split into 400 ms blocks, gated to ignore silence, and averaged into integrated loudness.

3

Compare & fix

See exactly how far your mix is from each platform target, so you know whether to push or pull before you export.

Why Prescosoft LUFS Checker

Your unreleased mix never leaves your machine — no upload, no cloud, no account.
Standards-accurate: the pipeline was verified against ffmpeg's ebur128 reference filter.
Free — no subscription, unlike Auphonic's loudness tools.
Works offline after the page loads.

Typical loudness meters

Youlean and similar require a download and install.
Web services ask you to upload your mix — before it's released.
Paid tiers for what is a few lines of DSP.
Ad-stuffed pages that interrupt your workflow.

Who is this for?

🎧

Music producers

Check your master against Spotify's -14 LUFS before uploading — without giving your unreleased track to a website.

🎙️

Podcasters

Podcast platforms normalize hard. See if your episode sits near the -16 LUFS dialog target so listeners don't get blasted or lost.

🎬

Video creators

YouTube turns everything down to -14 LUFS. If your mix peaks above -1 dBTP it can be rejected — check before you render.

Frequently Asked Questions

What is LUFS?

LUFS (Loudness Units Full Scale) is the standard measure of perceived loudness, defined by EBU R128 and ITU-R BS.1770. It applies a K-weighting filter that approximates human hearing, then averages over time with gating that ignores silence. A value of -14 LUFS is the common streaming target — louder than that is not "better," it's just louder.

What loudness target should I use?

YouTube, Spotify, and most podcast platforms normalize to about -14 LUFS integrated. Apple Music uses -16 LUFS, and Netflix targets about -27 LUFS for dialogue. The tool shows your measured integrated loudness against these targets so you can see how far off you are before exporting.

What is true peak?

True peak is the highest level the signal actually reaches after digital-to-analog conversion — it can exceed the sample peak because of inter-sample overshoot. It's measured with 4x oversampling. Streaming platforms reject files that exceed -1 dBTP, so this matters for mastering.

Why is my file showing a low LUFS?

Integrated loudness is a time-weighted average, so a file with lots of silence, quiet intros, or dynamic range reads lower than a constantly-loud file even if the peaks are identical. That's expected — check the short-term loudness and loudness range to see how dynamic the file is.

Is my audio uploaded anywhere?

No. The audio file is decoded and analyzed entirely in your browser using the Web Audio API. It never leaves your device — there is no server, no account, no tracking. That's the point: your mix is your intellectual property and it stays private.

What audio formats are supported?

Whatever your browser's Web Audio API can decode: typically MP3, WAV, M4A/AAC, OGG Vorbis, and FLAC. If a format fails to decode, try converting to WAV or MP3 first. Large files (over ~100 MB) may take a while since analysis happens locally.