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Room Axial Mode Calculator
Estimate the first three axial resonance frequencies along each dimension of a rectangular room.
Room length (m): 0.5–1000; Room width (m): 0.5–1000; Room height (m): 0.5–1000; Air temperature (°C): -20–50
Inputs stay on this page and clear on refresh.
Room Axial Mode Calculator
Room length (m): 5 Room width (m): 4 Room height (m): 2.5 Air temperature (°C): 20
- Length axis n=1 (Hz)
- 34.342000
- Length axis n=2 (Hz)
- 68.684000
- Length axis n=3 (Hz)
- 103.026000
- Width axis n=1 (Hz)
- 42.927500
- Width axis n=2 (Hz)
- 85.855000
- Width axis n=3 (Hz)
- 128.782500
- Height axis n=1 (Hz)
- 68.684000
- Height axis n=2 (Hz)
- 137.368000
- Height axis n=3 (Hz)
- 206.052000
Enter the internal length, width and height in metres and the air temperature. This tool models each pair of opposite, parallel rigid boundaries separately. For dimension D, the first three axial modes are f = n × c / (2D), where n is 1, 2 or 3 and sound speed c = 331.3 + 0.606 × T metres per second. T is in degrees Celsius. At 20 °C, c = 343.42 m/s; a 5 × 4 × 2.5 m room has axial fundamentals of 34.342, 42.9275 and 68.684 Hz respectively. Higher orders along each axis are integer multiples of its fundamental. Dimensions accept 0.5–1000 m, including decimals; temperature accepts −20–50 °C, including zero. Doubling one dimension halves only that axis’s predicted frequencies. Changing temperature changes all axes together. Equal frequencies from different axes are deliberately retained with their own axis and order labels: the nine values are not a sorted list of the nine lowest modes of the whole room. Values are computed before rounding and displayed to six decimals. This precision does not imply that wall dimensions or acoustic conditions are known that accurately. Use this as a reference when discussing low-frequency problems in rehearsal rooms or small venues. It does not measure resonance strength, decay time, pressure distribution or the response at a seat. It excludes tangential and oblique modes, wall compliance, absorption, openings, irregular geometry, coupled rooms, humidity and air movement. It cannot prescribe EQ boosts, treatment thickness or loudspeaker/listener positions. Confirm actual response and decay using appropriate measurements. Copy, download or print dimensions, temperature, all nine frequencies and these assumptions together. Empty or invalid inputs remove old results and disable export.
Methodology
How it works
Enter the internal length, width and height in metres and the air temperature. This tool models each pair of opposite, parallel rigid boundaries separately. For dimension D, the first three axial modes are f = n × c / (2D), where n is 1, 2 or 3 and sound speed c = 331.3 + 0.606 × T metres per second. T is in degrees Celsius. At 20 °C, c = 343.42 m/s; a 5 × 4 × 2.5 m room has axial fundamentals of 34.342, 42.9275 and 68.684 Hz respectively. Higher orders along each axis are integer multiples of its fundamental. Dimensions accept 0.5–1000 m, including decimals; temperature accepts −20–50 °C, including zero. Doubling one dimension halves only that axis’s predicted frequencies. Changing temperature changes all axes together. Equal frequencies from different axes are deliberately retained with their own axis and order labels: the nine values are not a sorted list of the nine lowest modes of the whole room. Values are computed before rounding and displayed to six decimals. This precision does not imply that wall dimensions or acoustic conditions are known that accurately. Use this as a reference when discussing low-frequency problems in rehearsal rooms or small venues. It does not measure resonance strength, decay time, pressure distribution or the response at a seat. It excludes tangential and oblique modes, wall compliance, absorption, openings, irregular geometry, coupled rooms, humidity and air movement. It cannot prescribe EQ boosts, treatment thickness or loudspeaker/listener positions. Confirm actual response and decay using appropriate measurements. Copy, download or print dimensions, temperature, all nine frequencies and these assumptions together. Empty or invalid inputs remove old results and disable export.
Method and assumptions documented by Techrider.live
2026-10-23
Frequently asked questions
Are these the nine lowest room modes?
No. They are orders 1–3 on each axis, shown separately. Tangential and oblique modes are excluded, and coincident frequencies remain visible.
Can this locate a resonance at a particular seat?
No. The model predicts ideal frequencies only, not spatial pressure, strength or decay. Measure the actual room.