# Audio Analyzer (Loudness and Clipping)

Measures a file’s LUFS loudness, true peak, clipping, silence and left-right phase in one pass. Use it to check the audio before you change its volume. The file is never uploaded.

- URL: https://tools.itlibra.com/en/audio-analyzer
- On-device・No upload
- Last updated: 2026-10-26

## How to use

1. Drop an audio or video file, or click “Choose file”. The file is read in your browser and is not sent anywhere.
2. The format and bit depth, integrated loudness, LRA, true peak, peak, RMS and clipping are listed. Longer audio takes longer.
3. Change the silence threshold (dBFS) and the shortest length, and the list of silent sections updates at once.
4. Click a place in the waveform or spectrogram, or move the time slider, to read the values at that time.
5. Save the result as CSV or text, or copy it.

## Use cases

- Before publishing, check that integrated loudness and true peak sit within the range you need
- Find when and how often an export clips (hits the ceiling) and where it happens
- Find the silent sections at the start or end of a recording, to choose where to trim
- Check for out-of-phase left and right channels before listening in mono

## What it does

### Same calculation as volume normalization

Integrated loudness, LRA and true peak use the same calculation functions as the volume normalization tool. Tests confirm that the same file gives the same values.

### Levels and clipping

Shows peak, RMS and DC offset, and lists each run of full-scale samples with its time and length.

### Silence and left-right correlation

Finds silent sections for a threshold and shortest length you set. For stereo, it computes the left-right correlation and flags a likely out-of-phase pair.

### Read values at any time

Click a place in the waveform or spectrogram to read the RMS, peak and momentary loudness at that time.

### Spectrum and spectrogram

Shows the average spectrum and a spectrogram of how frequencies change over time, with a colour legend.


## Supported formats

### Input

- Video: MP4, MOV, WebM, MKV and so on
- Audio: M4A, AAC, WAV, OGG, Opus, FLAC, MP3 and so on (what the browser can read)


## Capability matrix

| Feature | Support | Notes |
| --- | --- | --- |
| Integrated loudness (LUFS) | Supported | ITU-R BS.1770-4, for audio with 1 or 2 channels |
| Loudness range (LRA) | Supported | EBU Tech 3342 |
| True peak (dBTP) | Supported | Approximated with 4x oversampling |
| Maximum short-term (3 s) and momentary (400 ms) loudness | Supported | — |
| Peak, RMS and DC offset | Supported | — |
| Clipping count and times | Supported | Three or more samples in a row at −0.001 dBFS or louder |
| Silent sections (threshold and shortest length you set) | Supported | Judged in 100 ms steps |
| Left-right correlation (likely out of phase) | Partial | Stereo only; judged over the whole clip |
| Waveform, spectrum and spectrogram | Supported | The spectrogram is an approximation of about 480 columns |
| Codec and bit depth | Partial | Bit depth is shown for PCM (such as WAV) only |
| Pass or fail against a delivery target (such as −14 LUFS) | Not supported | Shows the numbers only; does not judge pass or fail |
| Audio with 3 or more channels (such as 5.1) | Not supported | — |
| Video analysis | Not supported | Only the audio track is analysed |
| Judging sound quality, noise or distortion | Not supported | — |
| Changing the audio (volume or editing) | Not supported | Analysis only |

## Limits & notes

- Up to 2 GB and 2 hours per file.
- Only the first audio track is analysed.
- Silence is judged in 100 ms steps; clipping needs three or more samples in a row.
- The spectrogram is an approximation of about 480 columns and 512 frequency bins.

## Privacy & safety

Reading, analysis, the charts and saving all happen in your browser. Neither the file nor the results are sent to a server.

## FAQ

### What is LUFS?

LUFS is a unit that expresses how loud sound seems to a listener. It is calculated with the ITU-R BS.1770-4 formula and shown as integrated loudness.

### Does it judge a delivery target such as −14 LUFS?

No. It shows the numbers only. Check the target value in the official guide of the platform you deliver to.

### How is clipping counted?

A run of three or more samples at −0.001 dBFS or louder counts as one clip. Peaks between samples are not part of this count; check those with true peak.

### What does a left-right correlation near −1 mean?

The left and right channels are almost out of phase. In mono they cancel each other, so the sound can become weak.

### Are the values the same as in the volume normalization tool?

Yes. Integrated loudness, LRA and true peak use the same calculation functions, and tests confirm the same file gives the same values. To change the volume to a target instead of only measuring it, use volume normalization.

### How is silence decided?

A section counts as silence when its RMS, measured every 100 ms, stays below the threshold you set (−60 dBFS by default) for at least the shortest length you set.