Why leave headroom on the mix bus at all?

A mastering engineer needs room to apply EQ, compression and limiting without the signal already touching 0 dBFS. Leaving a peak ceiling a few dB below full scale gives clean gain staging and prevents clipping when processing adds level.

How does the tool decide the headroom?

It estimates the limiter gain reduction from the gap between your current mix loudness and the target master loudness, then sets a peak ceiling that leaves room for that processing plus a fixed safety margin for inter-sample (true) peaks, typically around 1 dB.

What peak should I export my mix at?

A common practice is to leave mix peaks around -6 dBFS, but the ideal depends on how much louder the master needs to be. This tool tailors the figure: a mix already close to target loudness needs less headroom than a quiet mix that will be pushed hard.

What is the difference between sample peak and true peak?

Sample peak is the highest individual sample value. True (inter-sample) peak accounts for the analog waveform reconstructed between samples, which can exceed the sample peaks. Lossy codecs can also raise peaks, so leaving around 1 dB of true-peak margin avoids distortion after encoding.

Does louder mastering need more or less headroom?

More. A louder target (say -9 LUFS) from a quiet mix means a large amount of limiting, so you want generous headroom on the export. A gentle master close to your mix loudness needs far less limiting and therefore less headroom.

Mix Bus Clip Headroom Calculator

When you hand a mix to a mastering engineer — or master it yourself — the mix bus export should not already be slammed against 0 dBFS. This tool calculates the peak ceiling to set on your export so the mastering chain has clean headroom and the final master avoids clipping.

How it works

The amount of headroom you need depends on how much louder the master must be than your mix. The tool estimates the limiter gain reduction from the loudness gap:

gain to add (dB) = target LUFS - current mix LUFS

A mix at -18 LUFS targeting a -9 LUFS master needs about 9 dB of added loudness, most of it from limiting. The export ceiling is then set so that this processing, plus a fixed true-peak safety margin (about 1 dB), still fits under full scale:

export peak ceiling (dBFS) = -(true-peak margin) - headroom allowance

where the headroom allowance scales with the expected limiting. A bigger loudness jump means a lower (more negative) export ceiling.

Why a true-peak margin

Sample peaks are not the whole story. The analog waveform reconstructed between samples — the true peak — can exceed the sample values, and lossy codecs like AAC and MP3 can push peaks higher still. Leaving roughly 1 dB of true-peak margin keeps the encoded master clean.

Tips

Export at 24-bit so the lower level does not cost resolution.
Do not normalise the mix to 0 dBFS before mastering — that destroys the headroom this calculation creates.
For streaming, a -14 LUFS target with a -1 dBTP ceiling is a safe default; this tool refines the export level around that.

All calculations run locally in your browser.