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12notez

Free LUFS Loudness Meter & True Peak Checker

Free · No sign-up · Files never leave your device

What is LUFS?

LUFS (loudness units relative to full scale) measures how loud audio sounds, not how high its peaks reach. ITU-R BS.1770 (opens in a new tab) defines the measurement: the signal goes through a K-weighting filter that roughly follows how the ear hears each frequency, and quiet passages are gated out of the integrated reading. One LU is 1 dB. Streaming services and broadcasters set their targets in LUFS.

Loudness targets

WhereForIntegratedTrue peakSource
SpotifyMusic streaming−14 LUFS−1 dBTPsupport.spotify.com (opens in a new tab)
Apple PodcastsPodcasts−16 LUFS−1 dBTPpodcasters.apple.com (opens in a new tab)
EBU R 128Broadcast−23 LUFS−1 dBTPtech.ebu.ch (opens in a new tab)

How it works

  1. Step 1

    Your browser decodes the file

    The file is decoded by your browser's own audio engine, in this tab. Nothing is uploaded.

  2. Step 2

    It is measured to ITU-R BS.1770-4

    K-weighting, gated 400 ms blocks for integrated loudness, 3 second windows for short-term loudness and loudness range, and 4× oversampling for true peak (2× at 96 kHz, none at 192 kHz and above).

  3. Step 3

    You get plain answers

    Pick a target and the meter says whether the file is too quiet, too loud or clipping. Within 1 LU counts as on target.

Questions

Is my file uploaded anywhere?

No. The file is decoded and measured inside this browser tab. It never leaves your device.

What do integrated, short-term, loudness range and true peak mean?

Integrated loudness is the level of the whole file, in LUFS, with silence and very quiet parts gated out. Short-term loudness is measured over 3 second windows; the meter shows the loudest one and a graph over time. Loudness range (LU) is the spread between the quieter and louder parts, as defined by EBU Tech 3342. True peak (dBTP) is the highest level of the waveform, including peaks that fall between samples.

What level should my podcast or song be?

It depends on where it goes. The table on this page lists each target with a link to the page that publishes it. Pick one after measuring and the meter tells you how far off you are.

Why does my mono file read 3 LU lower than another meter?

BS.1770 measures a mono file as one channel. Some meters count mono as the same signal in both speakers, which reads about 3 LU louder. This meter follows the standard.

Which files work?

Any audio file your browser can play, usually MP3, WAV, M4A, FLAC and OGG, up to 100 MB. The browser decodes it at its own sample rate, so true peak can differ slightly from a meter that reads the file at its original rate.

Privacy: what runs where

  • Your audio is decoded and measured entirely in this browser tab. It is never uploaded.
  • No model or engine is downloaded from anywhere else: the meter is part of this page.
  • Nothing about your file is stored on our servers.

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