Loudness Compensation Calculator
This loudness compensation calculator helps when you listen quieter than your reference level: the ear hears less bass and treble. Enter both levels to get an approximate EQ boost that restores the balance — the idea behind a hi-fi "loudness" button.
⚠ Approximate guidance, not a precise calculation. This uses a simplified model of how equal-loudness contours (Fletcher–Munson / ISO 226) change with level — it captures the right shape (big bass boost, small treble boost, flat mids as volume drops), not exact ISO 226 dB values. Treat it as a starting point for a low-volume EQ tilt and trust your ears; it doesn’t measure or process audio.
Rough levels are fine — only the difference drives the compensation. A conversation is ~60 dB; a loud mix room ~85 dB.
Suggested boost per band (centre = no change, right = boost, left = cut):
Why Quiet Needs More Bass
Human hearing isn’t equally sensitive at every frequency, and the imbalance gets worse at low volume. The equal-loudness contours (Fletcher–Munson, updated as ISO 226) show that as overall level drops, the ear loses sensitivity to bass most of all, and to the top treble somewhat — while the midrange stays relatively constant. This is why the same sound can appear to have different tonal balance depending on playback volume: bass instruments recede and the mix sounds thin at low levels even if nothing has changed in the signal chain. The perceived loudness of bass at a given level is often expressed in phons, where the phon scale anchors each contour to its equivalent loudness at 1 kHz.
Loudness compensation counteracts that with a bass boost (and a touch of the highs) when you turn down — historically the "loudness" button on hi-fi amplifiers, first studied by Fletcher and Munson in the 1930s and later standardised as ISO 226. The amount of boost needed grows with how far below your reference you’re listening: this tool estimates that boost per octave band from the difference between your two levels. You can verify the effect of any EQ boost by playing a pure tone at specific frequencies before and after you apply the compensation settings in your EQ plugin or hardware.
Why "approximate"
A precise implementation evaluates the full ISO 226 equal-loudness contours at both levels and interpolates the difference. This calculator instead uses a simplified per-octave model tuned to the well-established shape of those curves. It captures the most important insight — large bass boost, modest high-frequency correction, flat mids — but the exact dB figures won’t match a lab measurement or a professionally calibrated loudness-contour lookup table. Use it as a starting tilt, set it by ear, and adjust to taste. Real-world listening room acoustics, headphone frequency response, and the spectral balance of the source material all influence what your ears actually need.