Audio / 05
Audio Normalizer: Loudness and Volume
Measure an audio file's loudness in LUFS and bring it to Spotify's −14, Apple Podcasts' −16, or broadcast levels, or raise or lower the volume by a set amount, without clipping and without an upload.
Audio Normalizer: Loudness and Volume: Loudness is measured as ITU-R BS.1770 defines it, the standard behind LUFS, and the true peak is estimated with 4× oversampling. The page then works out the gain that reaches your target without the true peak passing the target's ceiling, applies it, and measures the result again, so the figures shown are of the file you save. Runs 100% locally in your browser with zero server file uploads.
- Category
- Video tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
MP3, M4A, WAV, FLAC, OGG, or a video's soundtrack · up to 250 MB, nothing uploaded
Volume, loudness, and peaks
Two tracks can peak at the same level and still sound very different in loudness, because loudness depends on how much energy the sound carries over time, not on its single highest point. Streaming services and broadcasters therefore normalise by measured loudness, in LUFS, and set a separate ceiling for peaks.
When a service normalises a quiet track, it turns it up only as far as its peaks allow, or not at all; a loud track is turned down. Bringing a file to the service's target yourself means you hear what listeners will hear, rather than the service deciding.
When the target is out of reach
Speech recorded with a lot of peak-to-average range, such as a podcast with laughter or a raised voice, often cannot reach −16 LUFS with a 1 dB ceiling on gain alone. The usual answer is a compressor or limiter in an audio editor, which evens out the peaks, and then normalising again here. The LUFS meter shows where a file stands before and after.
How to use it
- Choose an audio file; its loudness and peaks are measured.
- Pick a target, such as a streaming service, or a fixed change in dB.
- Adjust and save as MP3, Ogg, or WAV, and check the result on the page.
Privacy & limitations
The file is processed in your browser and never uploaded. MP3 encoding uses LAME, free software under the GNU LGPL, loaded as a separate file; its source is at lame.sourceforge.io.
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Frequently asked questions
What loudness should I aim for?
Spotify normalises music to −14 LUFS and asks for true peaks below −1 dB. Apple Podcasts asks for −16 LUFS, within 1 dB either way, with peaks at or below −1 dB. European broadcasters use −23 LUFS under EBU R128, and US television −24 LKFS under ATSC A/85.
Why did it not reach my target?
Raising quiet audio also raises its peaks. When reaching the target would push them past the ceiling, the page stops at the ceiling and says so, because going further needs a limiter or compressor, which reshapes the sound. This tool only changes the volume, so the sound itself is untouched.
What is the difference between normalising and turning it up?
Peak normalising, the older method, raises a file until its loudest sample hits a level. Loudness normalising matches how loud it sounds, which is what streaming services do, so two tracks at −14 LUFS play at a similar volume even if their peaks differ.
Will saving as MP3 change the loudness?
Slightly. An MP3 encoder removes the very highest frequencies, which count towards loudness, so the file can come out a few tenths of a unit quieter than the audio fed in. The page decodes the saved file, measures it, and if it is off by 0.1 LU or more, corrects the gain and saves it again, so the figures shown are those of the file you download. Save as WAV if you will edit the file further.
Free tool · runs in your browser · no account required