Recording Studio Design Calculator

It sorts the three dimensions and compares their ratios against the range acoustician R.W. Bolt found produces the most even distribution of room modes, roughly 1 : 1.1–1.5 : 1.5–2.1. Rooms with dimensions close to equal, or in simple integer ratios like 1:1:2, stack multiple room modes on top of the same frequencies, producing audible bass buildup at some frequencies and nulls at others — a problem no amount of panel coverage fixes, since it's a geometry issue, not an absorption issue.

STC rating measures how well your walls block outside noise from entering the room, so higher STC (55+) means less external noise leaks in, which lets the calculator recommend a quieter NC-15 target. Lower STC ratings (below 45) mean more ambient noise is unavoidably present, so the calculator settles for a more achievable NC-25 target rather than recommending a noise floor your isolation can't actually deliver.

STC and RT60 solve two separate problems: STC is about keeping sound from crossing the walls, while RT60 and panel coverage are about controlling how sound reflects around inside the room once it's already there. A room can be extremely well isolated from outside noise and still sound harsh or boomy internally if its hard surfaces aren't absorbing enough of its own reflections, which is exactly what the panel coverage figure addresses.

The calculator uses the Sabine equation to find the total absorption your room needs to hit the target RT60, subtracts the absorption a bare room already provides at an assumed 0.05 coefficient, and divides the remaining shortfall by 0.8 (the NRC rating of standard 2-inch acoustic panels) to get square footage. A tighter target RT60, like 0.3s instead of 0.5s, requires proportionally more absorption and therefore more panel coverage.