Rescroll

Check your audio's loudness, in LUFS and true peak.

Drop in a song, a podcast episode or a video: its integrated loudness and true peak are measured to the BS.1770 standard, with what YouTube, Spotify and Apple Podcasts will make of it.

  • 100% free
  • No watermark
  • No sign-up
  • Full quality
  • Files stay on your device

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It runs in your browser. Nothing is uploaded.

How it works

How to normalize audio, free, in three steps.

  1. 1

    Drop in your video or audio

    MP4, MOV, MP3, WAV or M4A. Its loudness is measured right away, the way YouTube, Spotify and broadcasters measure it.

  2. 2

    Pick the target

    −14 LUFS for YouTube and Spotify, −16 for Apple Podcasts, −23 for broadcast, or your own. You see the gain it needs and how hard the peaks will be held down, before anything changes.

  3. 3

    Download it at the right level

    Audio comes back in its own format. In a video only the sound is re-made: the picture is copied across bit for bit, untouched.

Why this one

Free, with nothing held back, and nothing uploaded.

Measured like the platforms do

Integrated loudness to ITU-R BS.1770, the standard behind LUFS and EBU R 128, with the same gating, plus true peak with 4× oversampling.

Louder without clipping

Raising a quiet recording would push its peaks past 0 dB. A look-ahead limiter holds them under −1 dBTP instead, so it gets louder without distortion.

The picture isn't touched

For a video, only the soundtrack is processed and re-encoded. The video stream is copied as it is, so there's no quality loss and it's done in seconds.

The result, before you export

See the loudness it measured, the gain it will apply, the loudness it will land on and how often the limiter works, then decide.

Your file is opened and processed by your own browser. It is never sent to a server, so it stays private, and there’s no upload to wait for.

Reading a LUFS meter

Integrated loudness is the one number streaming services care about: the loudness of the whole file, measured in LUFS. A song at −8 LUFS will be turned down 6 dB by Spotify; a podcast at −24 LUFS sounds quiet next to others in a listener's queue.

True peak (dBTP) is the highest the waveform goes once it's turned back into sound, including peaks between the samples, which ordinary peak meters miss. Keep it under −1 dBTP and the file won't distort when a service converts it.

This meter reads both, using K-weighting and the standard's gating, and reads the same as other BS.1770 meters to within a tenth of a unit. If a file is off target, you can normalize it right here.

More from the loudness normalizer

Loudness normalizer

Bring any audio or video to −14, −16 or −23 LUFS, peaks held under −1 dBTP. Video untouched.

Make a video louder

Boost a quiet video to a proper level without clipping. Only the sound changes.

Normalize podcast audio

Bring an episode to −16 LUFS with peaks under −1 dBTP, Apple Podcasts' requirement.

Rescroll

Good sound is more than the right level.

Rescroll's AI video editor balances voice and music, removes background noise and filler words, and adds captions, so your video sounds and reads as polished as it looks.

  • Voice and music balanced automatically
  • Background noise and filler words removed
  • Captions in your brand's style
Try RescrollSee the AI video editor

Questions

The loudness normalizer: your questions, answered.

How do I check the LUFS of a song or video?

Drop the file on this page. Its integrated loudness in LUFS and its true peak in dBTP appear in a few seconds, measured on your device. Audio and video files both work.

What is LUFS?

LUFS (Loudness Units relative to Full Scale) measures how loud audio sounds over its whole length, not just how high its peaks go. It's weighted the way hearing is and ignores silence, which is why streaming services and broadcasters use it to play everything at the same level.

What loudness should I use for YouTube, Spotify and podcasts?

Spotify's published target is −14 LUFS, and YouTube is widely measured to play at about −14 LUFS too, though YouTube doesn't publish a figure. Apple Podcasts asks for −16 LUFS with true peaks under −1 dBFS. European broadcast (EBU R 128) is −23 LUFS.

What's the difference between normalizing and just turning it up?

Turning up the volume raises everything by the same amount, peaks included, so a recording with loud peaks clips long before it sounds loud enough. Normalizing to a LUFS target sets the overall loudness, and the limiter keeps the peaks in check while it does.

Is this loudness normalizer really free?

Yes. There's no price, no trial, no account and no limit on how many files you do. The loudness normalizer runs on your own device, in your browser, so it costs us nothing to run and we don't charge for it.

Does it add a watermark?

No. The file you download has no watermark, no logo and no intro or outro added. It's your file, changed only in the way you asked.

Is my video or audio uploaded anywhere?

No. The file is opened and processed by your browser, on your device, and never sent to a server: not to us, not to anyone. You can check: watch the Network tab of your browser's developer tools while it works, and you'll see the file is never sent anywhere.

How big a file can it handle?

There's no file size limit of ours. Files of several gigabytes work, because the file is read from your disk as it's needed rather than loaded all at once. What sets the pace is your device: a long 4K video takes longer on an older laptop than on a new one.

Which browsers does it work in?

Current versions of Chrome, Edge and Safari, and Firefox on a computer: any browser with the WebCodecs API for encoding video and sound. Some files, like iPhone HEVC video, need Chrome, Edge or Safari to decode. A computer is much faster than a phone for long videos.

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