日本語English

Volume Normalization and LUFS

When sound is quiet, or the volume differs from file to file, set it to a target in LUFS. -14 suits YouTube and Spotify, -16 Apple Podcasts, and -23 broadcast. The tool measures first, then changes only the gain, and keeps the true peak under -1 dBTP. Your file is never uploaded.

On-device・No uploadMobile friendlyWorks offline

Your files and input are processed only inside your browser on this device and are never uploaded to our servers.

Drop video or audio here

or

Choose a video (MP4, MOV, WebM, MKV and so on) or an audio file. Loudness (LUFS) and peaks are measured first, then the sound is set to the target. Limits depend on the device (PC: 2 GB and 4 hours per file).Accepts: MP4 / M4V / MOV / WEBM / MKV / M4A / AAC / WAV / OGG / OPUS / FLAC / MP3Paste (Ctrl+V) also works

How to use

  1. show1.mp4-18 LUFS
    show2.wav-23 LUFS

    Add audio or video (several is fine)

  2. show1.m4a+4.0 dB
    show2.m4a+9.0 dB

    Match the target (e.g. -14 LUFS)

  3. show1.m4a-18 → -14 LUFS
    show2.m4a-23 → -14 LUFS

    Measure again, check, then save

Bring files with uneven volume to the same target loudness in LUFS

  1. Drop a video or audio file, or click “Choose file”. Each file’s loudness (integrated, LRA and true peak) is measured.

  2. Choose a target: -14, -16 or -23 LUFS, or a custom value; then choose the output format.

  3. Check how much each file will be raised or lowered and the expected result. If a peak ceiling applies, the result says that the target is not reached.

  4. Click “Normalize and export”. The file you will save is measured again, and the waveforms before and after are shown. Check them, then save.

What it does

Measured with the standard formulas

Integrated loudness follows ITU-R BS.1770-4 (K-weighting and absolute and relative gates). Loudness range follows EBU Tech 3342, and true peak uses 4x oversampling.

Choose the reference

Pick -14 (YouTube, Spotify), -16 (Apple Podcasts) or -23 (broadcast), or type any value from -40 to -6.

Stops at the peak ceiling

If the true peak would pass -1 dBTP after the change, the gain stops there, and the result says the target was not reached.

Measures the saved file

The output is written and measured again, so you see the loudness of the file you will keep. The waveforms before and after are shown side by side.

Reads in pieces

The file is read a little at a time rather than loaded whole into memory, and you can stop part way.

Use cases

  • Raise a quiet video to -14 LUFS before uploading it to YouTube
  • Set several recordings to the -16 LUFS podcast target before publishing
  • Measure a meeting recording and raise it to a comfortable listening level
  • Match a broadcast clip to the -23 LUFS (EBU R128) reference

Supported formats

Input

Video: MP4, MOV, WebM, MKV and so onAudio: M4A, AAC, WAV, OGG, Opus, FLAC and so on (what the browser can read)

Output

MP3 (written with LAME)M4A (AAC)WAV (16-bit PCM)Opus (.ogg) and Opus (.webm)FLAC (only in browsers that can write it)

Capability matrix

FeatureSupportNotes
Integrated loudness (LUFS)SupportedITU-R BS.1770-4, for audio with 1 or 2 channels
Loudness range (LRA)Supported—
True peak (dBTP)SupportedApproximated with 4x oversampling
Gain change to the targetSupportedOnly the gain changes; no limiter or compressor is used
Any target from -40 to -6 LUFSSupported—
Stops at -1 dBTPPartialWhen the ceiling applies, the target is not reached; the result says so
Several files to one targetSupportedEach file is measured and set to the same target
Checking the result before savingSupportedThe output file is measured again and shown
Writing M4A and OpusPartialOnly in browsers with WebCodecs encoders (checked in Chrome; Safari and Firefox support is limited)
Writing MP3SupportedLAME (an open-source MP3 encoder) runs in your browser. About 0.3 MB is loaded the first time you choose MP3
Keeping videoNot supportedThe picture is not kept; only the sound is normalized
Audio with 3 or more channels (such as 5.1)Not supported—
Noise removal and sound improvementNot supportedOnly the volume is changed
Dynamics (compressor and limiter) controlNot supported—
Momentary and short-term loudness (M and S values)Not supported—

Limits & notes

  • Up to 2 GB and 4 hours per file on a PC. Phones: 300 MB and 1 hour.
  • Up to 10 files at a time.
  • The file is read twice (once to measure, once to write), so long videos take a while.
  • Silence, or sound shorter than 0.4 s, cannot be measured.

Privacy & safety

Reading, measuring, normalizing and saving all happen in your browser. The file is never sent to a server.

FAQ

Which LUFS should I use for YouTube?
-14 LUFS is widely known as the playback reference for YouTube and Spotify. Apple Podcasts uses -16 LUFS, and broadcast uses -23 LUFS (EBU R128). Choose the one that fits your use.
Will raising the volume make the sound clip?
The gain stops where the true peak would pass -1 dBTP. If it stops there, the result says the target was not reached. The tool does not compress the sound to make it louder.
What are LUFS and true peak?
LUFS measures how loud the sound seems to a listener, using the ITU-R BS.1770 formula. True peak (dBTP) is the highest level, including peaks that fall between samples.
Does the sound quality drop?
The gain only scales the sound, so its shape is unchanged. MP3, M4A and Opus are encoded again when saved, so they change slightly. WAV is rounded to 16 bits.
Is the picture kept?
No. Only the sound is normalized, and it is saved as an audio file such as MP3, M4A or WAV.
How do several files line up?
Each file is measured and set to the same target value. A file that the peak ceiling stops is shown as not reaching the target.

Audio Noise Removal

To reduce background noise in a recording or meeting, choose the audio or video, set the strength and click “Remove noise”. Compare the result with the original, then save it as 16-bit WAV. Your file is never uploaded.

No upload

Audio Converter and Video Audio Extractor

To get just the sound from a video, choose the video and an output format (MP3, M4A, WAV, Opus or FLAC). If the source audio is AAC, M4A is written without re-encoding, so the quality does not change. Your file is never uploaded.

No upload

Speaker Test

Press a button to play the left, center or right channel, a 20 Hz to 20 kHz sweep, or in-phase and out-of-phase noise. Every sound is generated in your browser, and the default volume is a quiet −24 dBFS.

No upload

Audio Editor

To cut unwanted parts of audio, drag on the waveform to select a range and press “Remove selected ranges”. To join clips, use “Join and edit” to set the order and any silence between them. You can save as WAV or MP3, or as M4A or Opus where your browser can write them. Your file is never uploaded.

No upload

Music Tag Studio

Edit and save the tags of MP3 and FLAC files in one table. Title, artist, album, track number, year, genre, lyrics and album art are supported, and garbled Shift_JIS tags common in old Japanese MP3s can be re-read and saved as UTF-8 / UTF-16. Audio data is not changed by a single byte, and everything stays on your device.

No upload

Screen Recorder

Record a screen, window or tab, your webcam and microphone without installing anything. Add a camera overlay or mix mic and tab audio. Recordings stay inside this device and are never uploaded.

No upload

Last updated: