Room Mode Calculator
Compute axial, tangential and oblique room modes, visualize modal distribution, and identify problematic resonances for studio and home theater design.
Room Mode Calculator
You can enter dimensions in meters or feet. Calculations are done internally in meters.
343 m/s ≈ 20 °C / 68 °F air temperature.
Most room modes of interest are below 200–300 Hz.
Room summary
- Dimensions
- 5.0 m × 4.0 m × 2.5 m
- Volume
- 50.0 m³
- Smallest dimension
- 2.5 m
- Schroeder freq. (approx.)
- ~ 160 Hz
Schroeder frequency is an approximate transition between modal and diffuse behavior.
Mode density overview
Calculated modes: –
Mode density per 10 Hz band will appear after calculation.
Mode distribution plot
Each dot represents a room mode at a given frequency. Axial, tangential and oblique modes are color-coded. Hover to see details; use the filters to focus on specific mode types.
Dense clusters of modes indicate frequencies where the room response may be uneven and require treatment or careful placement.
Detailed mode tables
Tables below list all calculated modes up to the selected maximum frequency. Click column headers to sort by frequency, type or mode order.
No modes calculated yet. Enter dimensions and click “Calculate modes”.
What are room modes?
Room modes are standing wave resonances that occur when sound reflects between the boundaries of a room. At specific frequencies related to the room dimensions, waves reinforce or cancel each other, causing strong peaks and deep nulls in the low‑frequency response.
In small rooms such as control rooms, home studios and home theaters, room modes dominate the bass region and strongly affect how accurately you hear low frequencies.
The room mode formula
For a rectangular room with rigid boundaries, the modal frequency for mode indices \(n, m, p\) is:
\( f_{nmp} = \dfrac{c}{2} \sqrt{\left(\dfrac{n}{L_x}\right)^2 + \left(\dfrac{m}{L_y}\right)^2 + \left(\dfrac{p}{L_z}\right)^2} \)
- \(f_{nmp}\): modal frequency in Hz
- \(c\): speed of sound (≈ 343 m/s at 20 °C)
- \(L_x, L_y, L_z\): room length, width and height in meters
- \(n, m, p\): non‑negative integers (0, 1, 2, …), not all zero
Axial, tangential and oblique modes
- Axial modes: involve one dimension only (e.g. (1,0,0)). They are usually the strongest and most audible.
- Tangential modes: involve two dimensions (e.g. (1,1,0)). They are weaker than axial modes.
- Oblique modes: involve all three dimensions (e.g. (1,1,1)). They are the weakest but numerous.
The calculator classifies each mode automatically and lets you filter by type to focus on the most problematic resonances.
How to interpret the results
1. Look for very low‑frequency modes
Modes below about 30–40 Hz in small rooms are hard to control and often cause large peaks or nulls. If your room has extremely low axial modes (due to very large dimensions), you may need substantial bass trapping or electronic correction.
2. Watch for mode clustering
When many modes fall within a narrow frequency band (for example 55–65 Hz), the response there can be very uneven. The distribution plot and mode density summary help you spot these clusters quickly.
3. Avoid simple dimensional ratios
If two dimensions are equal or simple multiples (e.g. 4 m × 4 m × 2 m), many modes will coincide, making problems worse. More “spread out” ratios such as 1 : 1.4 : 1.9 help distribute modes more evenly.
Practical tips to manage room modes
- Speaker and listener placement: avoid sitting or placing speakers at room centers or directly against walls, where strong nulls or peaks often occur.
- Bass trapping: use thick broadband absorbers in corners and along wall–ceiling intersections to damp low‑frequency modes.
- Symmetry: keep left/right symmetry around the listening position to avoid skewed stereo imaging while still optimizing for modes.
- Measurement: use a measurement mic and software (e.g. REW) to verify the calculated modes and fine‑tune treatment and placement.
Limitations of the model
This calculator assumes a perfectly rectangular room with rigid, reflective boundaries and uniform air. Real rooms have doors, windows, furniture and non‑rigid walls that shift and damp modes. Use the results as a design and troubleshooting guide, not as an exact prediction of your final response.
Room mode calculator – FAQ
What are room modes?
Room modes are standing wave resonances that occur between the boundaries of a room. At certain frequencies, reflections reinforce or cancel the sound, creating peaks and nulls in the frequency response that vary with position. They are especially important below about 200 Hz in small rooms.
Which room modes are most problematic?
Axial modes, which occur between two parallel surfaces (length, width or height), are usually the strongest and most audible. Tangential and oblique modes are weaker but can still cause issues, especially when many of them cluster around the same frequency band.
What is a good room ratio for studio acoustics?
There is no single perfect ratio, but classic recommendations such as 1 : 1.4 : 1.9 or 1 : 1.6 : 2.33 (height : width : length) help spread modes more evenly. The key is to avoid equal or simple multiple dimensions (e.g. cube‑like rooms), which cause many modes to stack at the same frequencies.
How accurate is this room mode calculator?
The calculator uses the standard analytical formula for rectangular rooms and assumes rigid, perfectly reflective boundaries. Real rooms deviate from this ideal, so the predicted frequencies are approximate. They are very useful for identifying likely problem areas, but final tuning should always be done with in‑room measurements and listening tests.
How can I fix problematic room modes?
Common strategies include:
- Moving the listening position and speakers away from room centers and boundaries.
- Adding broadband bass traps in corners and along wall–ceiling intersections.
- Using tuned absorbers (e.g. membrane or Helmholtz) for very strong single modes.
- Avoiding square or cube‑shaped rooms when building or selecting a space.