What Is a Limiter in Audio?

A compressor with an extreme ratio

Compression and limiting are the same process at different ratios. A compressor at 4:1 means for every 4 dB a signal rises above the threshold, only 1 dB gets through. At 10:1 it's more aggressive. At ∞:1 — infinity to one — nothing gets through above the ceiling. That's a limiter.

In practice, limiters are characterised by their near-zero attack time (they catch peaks before they clip) and their very specific ceiling behaviour. A brickwall limiter guarantees that no sample in the output exceeds the ceiling level.

What limiters are used for

True peak vs sample peak

Digital audio is stored as discrete samples. No individual sample can exceed 0 dBFS. But when that digital signal is converted to analog for playback, the conversion process (reconstruction filtering) can create peaks between samples that exceed the value of either adjacent sample — these are called inter-sample peaks or true peaks.

A conventional peak limiter set at -1 dBFS would still allow true peaks above 0 dBFS because it only monitors discrete samples, not the continuous reconstruction. A true peak limiter oversamples the signal internally, calculates where inter-sample peaks would occur, and catches those too.

Streaming platforms specify true peak limits (typically -1 dBTP) rather than sample peak limits for this reason. MP3 encoding in particular is known to create inter-sample peaks that can cause clipping on playback even when the source measured clean.

The relationship between limiters and loudness

A limiter alone doesn't make audio loud. It prevents peaks from exceeding a ceiling. What makes audio loud is gain — increasing the overall level of the signal. The limiter allows higher average levels by catching the peaks that would otherwise clip.

The typical mastering workflow: set a ceiling on the limiter (-1 dBTP), then increase the input gain until the desired loudness is reached. As input gain increases, the limiter works harder — more peaks hit the ceiling and get reduced. The louder the master, the more limiting occurs, and the more dynamic range is sacrificed.

This is what drove the loudness wars in commercial music production — engineers discovered that louder music seemed to sound better to casual listeners when compared A/B at different levels. The response was to push limiters harder and harder until the dynamic range of commercial releases was severely compressed. Streaming platforms now normalise playback levels (targeting -14 LUFS on most services), which removed the competitive advantage of extreme limiting — a louder master simply gets turned down.

Limiter settings