RandoziRoom Mode Calculator
Enter the length, width and height of a room and get its resonant frequencies up to the limit you choose, sorted and labelled as axial, tangential or oblique, with the pairs that fall close together.
First resonance
34.3 Hz
| Frequency | Order (L,W,H) | Type |
|---|---|---|
| 34.3 Hz | (1,0,0) | Axial |
| 42.875 Hz | (0,1,0) | Axial |
| 54.907 Hz | (1,1,0) | Tangential |
| 68.6 Hz | (0,0,1) | Axial |
| 68.6 Hz | (2,0,0) | Axial |
| 76.697 Hz | (1,0,1) | Tangential |
| 80.896 Hz | (0,1,1) | Tangential |
| 80.896 Hz | (2,1,0) | Tangential |
| 85.75 Hz | (0,2,0) | Axial |
| 87.868 Hz | (1,1,1) | Oblique |
| 92.356 Hz | (1,2,0) | Tangential |
| 97.015 Hz | (2,0,1) | Tangential |
| 102.9 Hz | (3,0,0) | Axial |
| 106.07 Hz | (2,1,1) | Oblique |
| 109.81 Hz | (0,2,1) | Tangential |
| 109.81 Hz | (2,2,0) | Tangential |
| 111.48 Hz | (3,1,0) | Tangential |
| 115.05 Hz | (1,2,1) | Oblique |
| 123.67 Hz | (3,0,1) | Tangential |
| 128.63 Hz | (0,3,0) | Axial |
| 129.48 Hz | (2,2,1) | Oblique |
| 130.89 Hz | (3,1,1) | Oblique |
| 133.12 Hz | (1,3,0) | Tangential |
| 133.95 Hz | (3,2,0) | Tangential |
| 137.2 Hz | (0,0,2) | Axial |
| 137.2 Hz | (4,0,0) | Axial |
| 141.42 Hz | (1,0,2) | Tangential |
| 143.74 Hz | (0,1,2) | Tangential |
| 143.74 Hz | (4,1,0) | Tangential |
| 145.78 Hz | (0,3,1) | Tangential |
| 145.78 Hz | (2,3,0) | Tangential |
| 147.78 Hz | (1,1,2) | Oblique |
| 149.76 Hz | (1,3,1) | Oblique |
| 150.49 Hz | (3,2,1) | Oblique |
| 153.39 Hz | (2,0,2) | Tangential |
| 153.39 Hz | (4,0,1) | Tangential |
| 159.27 Hz | (2,1,2) | Oblique |
| 159.27 Hz | (4,1,1) | Oblique |
| 161.11 Hz | (2,3,1) | Oblique |
| 161.79 Hz | (0,2,2) | Tangential |
| 161.79 Hz | (4,2,0) | Tangential |
| 164.72 Hz | (3,3,0) | Tangential |
| 165.39 Hz | (1,2,2) | Oblique |
| 171.5 Hz | (0,4,0) | Axial |
| 171.5 Hz | (3,0,2) | Tangential |
| 171.5 Hz | (5,0,0) | Axial |
| 174.9 Hz | (1,4,0) | Tangential |
| 175.74 Hz | (2,2,2) | Oblique |
| 175.74 Hz | (4,2,1) | Oblique |
| 176.78 Hz | (3,1,2) | Oblique |
| 176.78 Hz | (5,1,0) | Tangential |
| 178.43 Hz | (3,3,1) | Oblique |
| 184.71 Hz | (0,4,1) | Tangential |
| 184.71 Hz | (2,4,0) | Tangential |
| 184.71 Hz | (5,0,1) | Tangential |
| 187.87 Hz | (1,4,1) | Oblique |
| 188.06 Hz | (0,3,2) | Tangential |
| 188.06 Hz | (4,3,0) | Tangential |
| 189.62 Hz | (5,1,1) | Oblique |
| 191.17 Hz | (1,3,2) | Oblique |
| 191.74 Hz | (3,2,2) | Oblique |
| 191.74 Hz | (5,2,0) | Tangential |
| 194.03 Hz | (4,0,2) | Tangential |
| 197.04 Hz | (2,4,1) | Oblique |
| 198.71 Hz | (4,1,2) | Oblique |
46 pairs of consecutive modes within 3 % of each other: 68.6 and 68.6 Hz (0 %); 80.896 and 80.896 Hz (0 %); 85.75 and 87.868 Hz (2.47 %); 109.81 and 109.81 Hz (0 %); 109.81 and 111.48 Hz (1.51 %); 128.63 and 129.48 Hz (0.664 %); 129.48 and 130.89 Hz (1.09 %); 130.89 and 133.12 Hz (1.7 %)…
Dimension ratios: L/W 1.25 · L/H 2 · W/H 1.6. These describe proportions; they are not a quality score.
Model of a rectangular room with rigid, empty walls. It gives frequencies only, no amplitudes, and does not predict how a real room sounds. Your dimensions stay in your browser.
How it works
- Enter the length, width and height of the room in metres.
- Keep the speed of sound at 343 m/s (about 20 °C) or change it, and set the highest frequency you want.
- Filter the table by type of mode and read the frequencies with their (length, width, height) order.
- Set the closeness threshold to flag nearby modes, then copy the list. Dimensions are never sent anywhere.
What people use it for
Planning a home studio or listening room
See where the low-frequency resonances of the room fall before you place speakers or treatment.
Comparing two room shapes
Change one dimension and watch the first axial mode move.
Teaching acoustics
Show students the difference between axial, tangential and oblique modes with real numbers.
Questions
- What is the formula?
- f = c ÷ 2 × √((nx ÷ L)² + (ny ÷ W)² + (nz ÷ H)²), where c is the speed of sound and nx, ny, nz are whole numbers, not all zero. One non-zero index is an axial mode, two a tangential mode and three an oblique mode.
- Does it predict how my room sounds?
- No. It is the model of a rectangular room with perfectly rigid, empty walls. Real rooms have furniture, absorption, doors and non-rigid walls, so the frequencies and especially the amplitudes differ. Use it to understand the room, not to promise a result.
- Why is 343 m/s the default?
- It is the usual value for air at about 20 °C. The speed of sound changes with temperature, so you can type your own value.
- What are close modes?
- Neighbouring modes, in frequency order, whose gap is within the percentage you set (0 to 10 %). Being close is not automatically a defect; the page only flags them.