Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Length mode 1 (fundamental)
35.3
Width mode 1
47.1
Height mode 1
70.6
Length mode 2
70.6
Width mode 2
94.2
Height mode 2
141.3
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter room length (ft).
- 2Enter room width (ft).
- 3Enter room height (ft).
- 4Read your length mode 1 (fundamental) on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Room modes are standing waves that build up at frequencies where a room dimension is a multiple of half the wavelength, causing boomy bass in some spots and complete nulls in others — the reason a mix that sounds great in a treated studio can sound bass-heavy or thin in an untreated bedroom. This calculator computes the first three axial modes for each of a room's three dimensions (length, width, height) using the standard room mode equation, flagging problem frequencies to address with bass traps or speaker/listening position changes.
Worked example
Using the values the calculator loads with:
Inputs
- Room length: 16 ft
- Room width: 12 ft
- Room height: 8 ft
Results
- Length mode 1 (fundamental): 35.3
- Width mode 1: 47.1
- Height mode 1: 70.6
- Length mode 2: 70.6
- Width mode 2: 94.2
- Height mode 2: 141.3
What each field means
Inputs
- Room length (ft)
- The room length used in the calculation, measured in ft. Starts at 16 ft so you have a working example on load.
- Room width (ft)
- The room width used in the calculation, measured in ft. Starts at 12 ft so you have a working example on load.
- Room height (ft)
- The room height used in the calculation, measured in ft. Starts at 8 ft so you have a working example on load.
Results
- Length mode 1 (fundamental)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Width mode 1
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Height mode 1
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Length mode 2
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Width mode 2
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Height mode 2
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What do I actually do with these frequencies?
Any frequency shown close to another dimension's mode (within a few Hz) means that frequency will be especially problematic since multiple room dimensions reinforce it at once. Target those frequencies specifically with bass trap placement in room corners, where all axial modes have pressure maxima, and be skeptical of any mix decisions made in that frequency range from your main listening position.
Why are so many home studios built with roughly cube-shaped rooms a problem?
When length, width, and height are equal or simple multiples of each other, their room modes stack on the exact same frequencies instead of spreading out, creating one severe problem frequency instead of several milder ones. Non-integer-ratio dimensions (avoiding simple ratios like 1:1:1 or 1:2:2) spread modal problems more evenly across the spectrum.
Does this calculator cover tangential and oblique modes too?
No — this covers only axial modes (between two parallel surfaces), which are the strongest and most audible. Tangential modes (four surfaces) and oblique modes (all six surfaces) exist too but are progressively weaker and more complex to calculate; axial modes are the right starting point for basic room treatment planning.
What speed of sound value does this use and why does it matter?
This uses 1,130 ft/sec, the standard approximation for dry air at roughly 70°F. Speed of sound changes with temperature and humidity, but the variation across normal room conditions shifts mode frequencies by only a percent or two, which doesn't meaningfully change your treatment decisions.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Room Mode Frequency Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/room-mode-frequency
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/room-mode-frequency" target="_blank" rel="noopener">Room Mode Frequency Calculator — RevenueLab</a> (2026).</p>
Source: [Room Mode Frequency Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/room-mode-frequency) (2026).