Measure loudness in LUFS, in your browser
Integrated, short-term and momentary LUFS, loudness range and true peak to BS.1770-4 and EBU R128, checked against reference tones. Free, no upload.
Drop your audio file here
It opens in seance in this tab. The file stays on your computer.
- Opens
- WAVMP3FLACOGG
- Runs in
- Your browser
How to measure a file#
- Drop the audio file on the box above, or open seance and press Load audio.
- Open Meter, pick a target and press Measure.
- Read the numbers, and the short-term loudness over time against your target.
What it reads#
- Integrated loudness in LUFS: the whole file, with quiet passages gated out the way BS.1770-4 says.
- Short-term (3 s) and momentary (400 ms) maximum.
- Loudness range in LU, to EBU R128.
- True peak in dBTP, found by oversampling four times, and the plain sample peak.
- PLR, the true peak minus the integrated loudness.
- For stereo files, the correlation between the channels, and an average spectrum.
Targets to compare against: −14 LUFS for streaming, −16 for podcasts, −23 for EBU R128 broadcast and −9 for a club master.
Reading the timeline#
Below the numbers, seance draws the short-term loudness over the whole file with your target as a line, so you see which passages sit above it and by how much. A master that sits well above the target will be turned down by a streaming service. A second graph shows the stereo correlation every 400 ms: values near −1 mean the channels cancel when summed to mono.
How we know the numbers are right#
The standard gives reference readings for plain sine tones. The audio suite measures them on every build:
| Test signal | Must read | seance reads |
|---|---|---|
| 997 Hz sine at full scale, one channel | −3.01 LUFS | −3.01 LUFS |
| The same sine, 20 dB lower | −23.01 LUFS | −23.01 LUFS |
| 997 Hz sine at full scale | 0.0 dBTP | 0.00 dBTP |
| Sine whose peak falls between samples, samples at −3.01 dB | close to 0 dBTP | −0.07 dBTP |
Questions#
Is this the loudness Spotify and YouTube use?#
They normalise playback by a loudness measure of the same family. Measuring to BS.1770-4 tells you how far your master sits from their reference, commonly given as −14 LUFS. How each service turns that into a gain change is up to the service.
Does it meter live input?#
No. It measures a file. Load the bounce of your mix.
Is my audio uploaded?#
No. Decoding and measuring happen in the page, on your computer.