Loudness Meter

A loudness meter measures how loud audio feels to human ears, in LUFS — not just peak levels. This free online meter shows momentary, short-term, and integrated LUFS plus true peak, so you can check your mix against Spotify, YouTube, and Apple Music targets.

Key Takeaways

• LUFS (Loudness Units relative to Full Scale) measures perceived loudness per the ITU-R BS.1770 standard.
• Momentary (400 ms), short-term (3 s), and integrated (whole track, gated) answer different questions.
• Streaming targets: Spotify −14, YouTube −14, Apple Music −16 LUFS; keep true peak under −1 dBTP.
• Platforms turn loud masters down — crushing your track gains nothing on streaming.
• True peak catches inter-sample overs that regular peak meters miss.

What Is a Loudness Meter?

A loudness meter measures perceived loudness in LUFS (Loudness Units relative to Full Scale), following the ITU-R BS.1770 standard — unlike a peak meter, it models how human ears actually hear. Two tracks peaking at 0 dBFS can feel wildly different in volume; at matched LUFS they feel the same. That is why every streaming platform normalizes on LUFS, not peaks.

This meter analyzes your microphone or playback input in real time, displaying all three standard time windows plus true peak. Use it to check a mix before upload, compare masters, or learn how loudness works by watching the numbers move as music plays.

How This Loudness Meter Works

Press Start Loudness Meter and the page captures audio via the Web Audio API, then runs a K-weighted loudness algorithm modeled on ITU-R BS.1770: a high-shelf boost above ~1.5 kHz plus a high-pass filter, mimicking ear sensitivity, followed by mean-square energy averaging over sliding windows.

Methodology: momentary = 400 ms window (catches sudden hits), short-term = 3 s window (verse/chorus balance), integrated = gated whole-session average (absolute gate −70 LUFS, relative gate −10 LU — silence doesn't drag it down), true peak = 4× oversampled inter-sample peak. The history graph plots short-term LUFS over time. Validation method: play a 1 kHz sine at −20 dBFS — the meter should read approximately −20 LUFS momentary, since K-weighting is near-flat at 1 kHz.

Last reviewed: October 2026. Algorithm follows ITU-R BS.1770-4 principles; platform targets per Spotify, Apple, YouTube, EBU R128, ATSC A/85 published specs.

LUFS, Gating, and True Peak: Worked Example

Integrated LUFS isn't a simple average — gating excludes silence so intros don't cheat the number:

1. Split the track into 400 ms blocks, compute each block's K-weighted loudness
2. Drop blocks below −70 LUFS (absolute gate — digital silence)
3. Compute the average, then drop blocks more than 10 LU below it (relative gate — quiet verses stay, fade-outs go)
4. Average the survivors = integrated LUFS

True peak example: a master peaking at −0.1 dBFS (sample peak) can still hit +0.4 dBTP between samples — invisible to normal meters, but it clips when YouTube re-encodes to AAC. That half-decibel of hidden overs is exactly what the true-peak readout exists to catch: keep it under −1 dBTP and encoding stays clean.

How to Use the Loudness Meter

1. Press Start Loudness Meter and allow microphone access (or route your DAW output to the input).
2. Play your track from start to finish for an integrated reading.
3. Watch Momentary for sudden jumps — a snare 6 LU above the verse may need taming.
4. Watch Short-Term to compare sections: verse vs chorus balance at a glance.
5. Read Integrated at the end — this is the number platforms normalize to.
6. Check True Peak: if it exceeds −1 dBTP, lower your limiter ceiling and re-render.
7. Compare against the platform table below to decide if your master is ready.

Reading Your Result: Platform Targets

Match your integrated LUFS and true peak against where the track is going:

Next step per result: integrated within ±1 LU of target and true peak under −1 dBTP → ship it. Louder than −10 LUFS → expect turn-down; check it still sounds open. True peak over 0 dBTP → lower the limiter ceiling, don't just turn down (peaks stay).

Why Spotify Turned Your Track Down (Normalization Truth)

Here is the asymmetry most pages skip: platforms always turn loud tracks down to their target, but only turn quiet tracks up if peak headroom allows — and never with limiting. So a −8 LUFS crushed master gets turned down to −14 and keeps all its squashed artifacts, while a dynamic −14 LUFS master plays untouched and sounds better.

The practical takeaway: −14 LUFS is a playback level, not a mastering law. A punchy −9 LUFS master turned down to −14 retains its character; a track strangled to exactly −14 "to avoid turn-down" gains nothing and often loses life. Master for the song, keep true peak under −1 dBTP, and let normalization do its job.

Limitations

• Browser implementation, not a certified meter. Values follow BS.1770 principles but this isn't a calibrated compliance instrument for broadcast delivery.
• Mic/system path colors readings. OS enhancements, AGC, or Bluetooth codecs alter levels — measure from a clean file playback path for mastering decisions.
• Integrated needs a full pass. A 10-second snippet's integrated value is meaningless; play the whole track.
• True peak is estimated. 4× oversampling catches most inter-sample peaks, but codec-induced overs (AAC/MP3) can only be checked by encoding.

Loudness Meter vs Alternatives

Frequently Asked Questions

Note: this tool is for educational and pre-mastering checks. It is not a certified broadcast compliance meter.

Related tools: decibel meter for SPL readings, waveform visualizer to see your audio, microphone test to check input levels, and audio trimmer to cut silence before measuring.