LUFS Loudness Meter (EBU R128)

Measures loudness according to broadcast standards (ITU-R BS.1770) including integrated LUFS, true peak, loudness range, and short-term/momentary statistics.

Parameters

Parameter Type Default Description
file_path string required Path to audio file
channel string "all" Channel to analyze: "left", "right", or "all"

Example Output

$ analyze_loudness mix-v3.wav

Loudness Analysis Integrated: -14.2 LUFS True peak: -0.8 dBTP Range (LRA): 7.3 LU Short-term: -12.1 LUFS (max) Momentary: -9.4 LUFS (max)

What the Numbers Mean

  • Integrated LUFS — The overall loudness of the entire file. This is the number streaming platforms use for normalization. Spotify targets -14 LUFS, Apple Music -16 LUFS, YouTube -14 LUFS.

  • True Peak (dBTP) — The actual waveform peak including inter-sample peaks. Most platforms require -1.0 dBTP or lower. Values above -1.0 risk distortion during codec conversion (MP3/AAC).

  • Range (LRA) — The difference between quiet and loud sections in Loudness Units. Higher = more dynamic. Classical music: 10-20 LU. Pop/rock: 5-9 LU. EDM/hip-hop: 3-6 LU.

  • Short-term — Loudness measured in 3-second windows. The max value shows the loudest sustained passage. Useful for identifying sections that might trigger limiters.

  • Momentary — Loudness measured in 400ms windows. The max value shows the loudest transient burst. Compare to integrated to understand peak-to-average ratio.

Example Prompts

Streaming check

Is my mix loud enough for Spotify? Analyze the loudness of master.wav

True peak safety

Check if my master has any true peak issues at master-final.wav

Dynamic range

What’s the dynamic range of my mix? Is it over-compressed?

Pro tip

If your true peak exceeds -1.0 dBTP, don’t just turn down the master fader. Use a true peak limiter set to -1.0 dBTP ceiling — it catches inter-sample peaks that a standard limiter misses.