Room sizes compliance with international standards and recommendations
* initial sizes have to be given in meters
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Insert room sizes in meters into corresponding cells. Use full stop as separating character. The program will automatically calculate apparent room sizes and will display the results as yellow spot in the diagram on the right.
If the room proportions correspond to the recommended meanings*, the yellow spot will be situated inside the outline, shown by corresponding color line

Room linear sizes, m
Height, H  
Width, W  
Lenght, L  

 Relative room sizes H W L
Room cubing, cub.m.





The most well-known proportions of room sizes
Source H W L
L. W. Sepmeyer, 1965 1,00 1,14 1,39
L. W. Sepmeyer, 1965 1,00 1,28 1,54
L. W. Sepmeyer, 1965 1,00 1,60 2,33
M. M. Louden, 1971 1,00 1,40 1,90
M. M. Louden, 1971 1,00 1,30 1,90
M. M. Louden, 1971 1,00 1,50 2,10
Richard H. Bolt, 1946 1,00 1,50 2,50
Richard H. Bolt, 1946 1,00 1,26 1,59
IEC 60268-13, 1998 1,00 1,96 2,59
The Golden Ratio, 1968 1,00 1,62 2,62
Dolby Lab Recomendations 1,00 1,49 2,31
Worst ratio (RPG Inc.) 1,00 1,07 1,87

Room sizes proportions from the chart are shown as a red spot in the diagram.
It’s possible to calculate not only acceptable, but the most optimal room proportions for each definite case with the help of program-analytical approach by Trevor Cox.

Trevor Cox recommendation, 2004

For reference only, there are results of computer calculations for room proportions according to Trevor Cox (Trevor Cox, 2004) methods given as diagram background.
The calculations are made for optional rooms with cubing of 50, 100 and 200 cubic meters.

Dark areas on diagram background correspond to room sizes with the smoothest modal characteristics; consequently, these corresponding proportions are more acceptable while building music-rooms and control rooms. “Best” proportions areas are shown in black color, gray color is given to areas of acceptable proportions, and others are shown in white.
The diagram shows that increase in room cubing leads to increase in number of acceptable proportions of line sizes, i.e. bigger rooms are less sensitive when it comes to inequality of modal characteristics at low frequencies.

Choose room cubing, cub.m.

relative room length (L/H)
relative room width (W/H)

Image © Prof Trevor Cox, University of Salford, UK


* Richard H. Bolt recommendations Note on the normal frequency statistics in rectangular rooms. J.Acoust.Soc.Am. 18(1) 130-133, 1946 3/2(W-1) < L-1 < 3(W-1)
2 < W+L<4
EBU / ITU recommendations European Broadcasting Union, TR R22, 1998 International Telecommunication Union ITU-R  BS.1116-1, 1998 1.1W/H <= L/H <= (4,5W/H) - 4
W < 3H, L < 3H,
5% protective rule
IEC recommendations IEC TR 60268-13 Sound System Equipment- Part 13 Listening tests on loudspeakers, 1998 W/H <= L/H <= (4,5W/H-4)
W/H < 3, L/H < 3
Trevor Cox recommendations Room Sizing and Optimization at Low Frequencies Audio Eng. Soc., Vol. 52, No. 6, 2004 1.1W/H <= L/H <= (1,32W/H) + 0,44
W < 3H, L < 3H,
5% protective rule
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